Before readers accuse me of being an alarmist, the headline above closely tracks the headline of the Bloomberg story by Peter Coy, How a Covid-19 Vaccine Could End Up Helping the Virus Spread. The striking bit is once you understand the medical issues Coy is raising, you’ll see his concern is legitimate. The short version is just because you got the vaccine does not necessarily mean you can’t infect others.
Until the rise of anti-vaxxers, with unseemly rush to get a Covid vaccine legitimating the vaccine refusnik (or “wait and see”) position, it was reasonable to assume that citizens would dutifully get vaccinated against dangerous contagious diseases, as much for themselves as everyone else. The high uptake rate would reduce the risk of anyone catching the disease to a very low level.
But Covid presents a very different picture. Even with enthusiastic coverage of the progress on vaccine development, a big slug of Americans still aren’t on board. A survey a few months back found only 50% would get a Covid vaccine. Even with infections and deaths on the rise, an end-of-October STAT/Harris poll found that fewer than 70% would take a vaccine with 70% efficacy:
Needless to say, this survey also shows that Americans are bad at math. Why would fewer people be on board with 90% efficacy versus 75%?
But separately, unless there’s a lot more propaganda messaging and education, the actual take-up numbers are sure to be lower if a vaccine had side effects serious enough to have decent odds of the recipient needing to take a day off from work.
And even if we assume that more people eventually become willing to get jabbed, it’s still going to take time to roll out a vaccine. The EU said they can’t vaccinate everyone before 2022. America’s access to healthcare and geographic spread means we’re pretty certain to be on a slower timetable.
And now….drumroll….here is the nub of Coy’s concern:
If everyone in the world is vaccinated, or has developed antibodies through exposure to the disease, there will be no problem. But in the early going, when only some people are protected, they could unwittingly spread the disease to people who are still vulnerable. The vaccinated people might stop wearing masks and social distancing since they aren’t themselves at risk anymore. They could be carrying the SARS-CoV-2 virus, even if they’re not getting sick from it.
How big a problem this might be is hard to say, because we don’t know for sure if immunized people are capable of shedding infectious virus. It’s possible that their antibodies will eradicate any infection pretty quickly, so they might just shed viral debris….
It’s also not yet clear how much protection the Pfizer-BioNTech vaccine and others would provide. The gold standard is to achieve sterilizing immunity, which is so strong that the virus can’t get a grip in the body at all—meaning that vaccinated people are safe to others. The human papillomavirus vaccine provides sterilizing immunity, for example. But sterilizing immunity is hard to achieve with viruses such as SARS-CoV-2, which enter through the respiratory system. The only sure way to know if the vaccine provides sterilizing immunity would be to check whether trial subjects who remain free of Covid-19 have been exposed to it, by tracing their contacts.
The Pfizer-BioNTech vaccine and others might provide just functional immunity—protecting people from the full-blown disease but not from carrying the virus. Functional immunity may also be what people get from being infected by the disease itself. They can catch it again, but will have fewer, if any, symptoms. We already know that people who are asymptomatic can spread Covid-19. In fact, that’s one of its scariest characteristics.
Coy then quotes an Australian researcher who is working on four vaccines, but not Pfizer’s. He doesn’t dispute Coy’s contention, but argues that preventing “clinical disease” will still reduce transmission, since they won’t be coughing Covid cooties. And we do know that asymptomatic cases don’t shed as much virus as symptomatic ones.
However, Coy’s point is a fair one: if a fair number of the vaccinated quit wearing masks and stop social distancing, the disease could still keep spreading: ” But if people who get vaccinated throw caution to the winds, it’s possible they could get a lot of other people sick.”
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Good post.
Also the vaccine trials look suspect to me. Someone on another message board found this tidbit in a press release.
https://apnews.com/article/pfizer-vaccine-effective-early-data-4f4ae2e3bad122d17742be22a2240ae8
What????? They didn’t test everyone? How is this an fda approved trial?
I believe there was a British study that showed that 75 percent of those who tested positive had no symptoms. So if the vaccine isn’t really a fix for the pandemic politicians are going to have a hard time pushing mandatory vaccination (which Biden is toying with?). Meanwhile deaths are down in part because hospitals and doctors have become more experienced at dealing with the disease. Perhaps we should be concentrating on treatment rather than a ‘cure but not really’ vaccine which, if nothing else, will provide a 100 percent chance of financial bonanza for Pfizer.
Yep, I’ve seen anywhere from 30% asymptomatic rate to that study with 75%.
The supposedly high asymptomatic rate is part of the reason you’d go for a vaccine in the first place, to stop the invisible spread that can be so hurtful to the people who get a bad case of the disease or have underlying conditions.
But the vaccine trials then ignore asymptomatic people?
Makes no sense except for what you end with, which is that someone is making a crap load of money.
The first thing to understand is that the concept of “case” in regard to Corvid19 is purely a matter of definition. Originally the term meant a patient who was under a doctors care and had been diagnosed with a particular illness. In the face of the pandemic panic, the term has morphed into “an individual who has tested positive for the presence of Corvid”. While there are many different tests employed worldwide, the two major types are the antibody test and the “gold standard” PCR test in which a swab from deep in the nasal passage is retrieved and sent to a laboratory where it is amplified until the presence of active nano-particles of the virus can be identified.
Antibody tests are quick, easy, and inexpensive but notoriously inaccurate, sometimes yielding 30-50% positive scores where no active virus molecules are present.
By contrast, the PCR test is inherently slow and expensive because it requires a preogressive amplification process that must be carried out in a properly equipped laboratory. The actual test is quite accurate, but the devil is in the details. In practice the nasal swab is amplified until the presence of the Corvid corona-virus is detected , at which time the individual being tested is deemed positive for the virus. The typical number of amplifications used is 40, at which point the test is deemed positive or negative— an up or down score. This has nothing to do with whether the tested individual has or will experience symptoms of Corvid19 (the disease) or will progress to a life threatening stage or death. The extent of viral loading is ignored, at least on the pass or fail score which is the only one recorded. Even the inventor of the test objects that it was never intended to be used in the way it is now and is essentially useless in its current form..
If the level of amplification were set somewhere around 30 the number of “cases” would drop radically as the test identifies those who have a higher probability of advancing toward critical illness and misses many who will never progress to the point where they are noticeably ill or are contagious to others. To take another example, if you had a mild or unnoticed Corvid19 infection several months past and now take the PCR test because you want to fly internationally or to Hawaii you will likely fail and be denied entry because your T-cell immune system has been “educated” to identify and combat the Corvid virus and you are effectively immune and totally non-contagious. .
On the other hand if the amplification process is carried out 50 times almost everyone in the USA will test positive for Corvid19 as the sensitive test “microscope” bores down toward the atomic level and finds the one molecule of Coronavirus that they have encountered floating in the air.
The ballooning number of cases that the MSM uses to make their headlines pop and the Politicians use to herd their followers into submission could easily become a political windfall. Just change the measurement protocol and you will be a hero!! Or better yet as Carolinian suggests, concentrate on treatment rather than merchandising of miracle cures to pump and dump stock pricing.
Cuba: Universal fee public heath care, 2.8 times more doctors than in the USA, Anti-viral medicines, No vaccine, No ventilators, Daily monitoring by an army of heath care providers—– 11 million people: 139 deaths. vs New York with 33,000.
this was good up until :
“To take another example, if you had a mild or unnoticed Corvid19 infection several months past and now take the PCR test because you want to fly internationally or to Hawaii you will likely fail and be denied entry because your T-cell immune system has been “educated” to identify and combat the Corvid virus and you are effectively immune and totally non-contagious. .”
T cells have noting to do with PCR tests. You might fail because you have virus particles that are no longer infectious.
Of course T cells are not the subject of PCR tests and I didn’t imply so. An effective immune system may be able to repel the Corvid attack and maintain heath without destroying all the invader virus. And under those circumstances the patient would still test positive with a conventionally administered 40 amplification PCR test.
“Universal free public health care” Not fee!
I have run lots of PCRs in my day in a research setting. It is sensitive, but usually not to 1 copy of viral template without a lot of optimization.
The ‘amplification level’ you mention I think is the Ct (crossing threshold). Any skilled operator knows you can get spurious amplification in late cycles (>35) and to take them with a grain of salt. Most diagnostic tests will be probe based PCRs which have less issue with this spurious amplification than other methods.
Sure, viral load is important to infectivity and a patient with a positive PCR could be noninfectious. PCR will not tell you that. However, if you are positive by PCR, you are very likely infectious and prudent public health policy would be to isolate until negative.
Makes you wonder how much they want to really stop the spread.
That PPP was a nice boost for a lot of organizations, the bigger the better.
Anecdotally, I know medical staff who have tested positive for antibodies and they have certainly become far more casual in their daily lives as they consider themselves immune. I have absolutely no doubt that if a vaccine is introduced then the first social phenomenon will be large scale intimate partying by those vaccinated. In fact, this may be the best way to encourage young people to get the vaccine (a little like how blood donors in Ireland always got a Guinness after donation).
A related issue may be the problem of an increasing number of new strains. I wonder if there is a risk of people with immunity from previous exposure or a vaccination becoming carriers for a novel strain.
I’ve been wondering about “rebound effects” for Michael Mina’s rapid testing push too. When people don’t understand the tools they’re given they will push them beyond the design intent, as illustrated by morons uploading videos to Youtube of them sitting in the back seat with their Tesla on Auto Pilot on the motorway. It sounds like the Trump White House was using rapid antigen tests and treating the results as being as conclusive as PCR.
“If everyone in the world is vaccinated, or has developed antibodies through exposure to the disease, there will be no problem…”
So it has been officially determined that Covid-19 is like the chicken pox unlike all the other corona viruses that have limited term anti-body protection?
We’ve already seen this phenomenon of those classed as having a lower risk of contracting severe to fatal cases of covid (e.g. young people) becoming super spreaders, the early stages of vaccine availability will be a 2.0 version of this. Lockdown fatigue and a longing for a return to a full, non-attenuated version of normal life combined with the near-constant messaging from the beginning of the pandemic that a vaccine will be the only way to achieve a return to said normalcy almost guarantees that vaccination will create an air of invincibility in those who get it.
Imploring the vaccinated to continue wearing masks and practising social distancing will be a tough sell. I also notice that those touting a vaccine as the coup de grace that will end the pandemic once and for all have failed to consider the not inconsiderable number of people who have clearly stated they will not be taking one, and planned contingencies for this. A mandatory, state decreed vaccination program for every citizen is obviously impossible in all but the most authoritarian countries, so, while a vaccine will certainly move the needle in the fight against the corona virus, I doubt it will deal a final blow to the pandemic as many hope it will.
I agree with Yves on the necessity of more and continuous messaging/education on the benefits of wearing masks in the “we have a vaccine now!” world. If I understand correctly, mask wearing will not only help in spreading/getting Covid-19, but also common cold and flu. For sure, hand washing and other forms of proper hygiene should be assumed as beneficial, but these personal tactics are somewhat hidden from the public’s view. It is mask wearing that is likely the “tough sell” as Thuto puts it as it appears to communicate to (some/many) in the general public that you are the anxious/nervous/germaphobe type. But wasn’t this sort of thing the case with seatbelts and condoms? It seems to me it was through education that allowed us to finally “sell” the long term benefits. Check back with me in 5-10 years, but I’m all in for mask wearing (especially indoors-public) for the rest of my life.
I mean, I have seen little education here in the US. There is no education. Was in my rural grocery store yesterday and the mask wearing is perfunctory at best.
Few understand how to wear it. I think I could count on one hand the number of people wearing a mask in effective way (ie no gaps and fully sealed). and the bandanna is not going to do it. The new this is face shields with no masks. It’s a joke.
Where are the n95s? Why aren’t they being distributed?
Yes. And there was that blurb from MIT about a month ago which stated that they thought and were testing their hypothesis that just wearing masks provided a gradual immunity to the population by limiting the viral load to one that the body can handle without getting very sick. Which makes very good sense. But no follow-up on that one. If everyone continues to wear masks for a long enough time to ensure the pandemic is “over” that could work. The question is, How long? Even with the vaccine it seems to be the question that can’t be answered. Because, as in China, pockets of Covid keep popping up. And masks are better at preventing an outbreak of serious illness, it would seem.
Well this raises some interesting questions about social life and the extent to which we are party to some kind of social contract. I think some mask-wearing people got a bit righteously annoyed by people not wearing masks in situations where it was recommended — in a bus, in a shop, etc. I wear a mask that protects myself and you; then you should reciprocate. Now with the vaccine the poles may be reversed. I have been vaccinated and you haven’t? Why should I wear a mask to protect you if you have deliberately refused a vaccine? Your problem is not my problem. It adds piquancy to the situation because anti-vaxxers are highly likely to be anti-mask too.
Of course i know the real scenario will be considerably more complicated. Not everybody will be able to get the vaccine for a considerable period of time. So there will often be, in any social setting, people who have been able to get the vaccine and those who haven’t been able to — and those who choose not to do so. Nevertheless covid19 does raise interesting questions about rights, mutual responsibilities and the social contract.
There is also the matter of trust. Trust in authorities has largely evaporated for very good reasons, so if the authorities recommend or force any technique to control COVID-19 (or any other disease) large numbers of people will be rightly skeptical and are likely to resist, as we have already observed with masks. This especially applies to vaccination by the usual methods, which involve the introduction into one’s body of unfamiliar or unknown substances which it cannot reject. I know several people who reacted badly to vaccination (indeed, one died within minutes of the injection) and such stories will be spread rapidly via social media. Additional factors are the political and financial elements of the situation, including the desire of big corporations to make lots of money really really fast. Many have observed that the kind of people who rise to high governmental and corporate power are mostly sociopaths indifferent to the welfare, indeed, the lives, of lesser beings. I doubt if I need to cite the well-known examples demonstrating the sociopathy. Hence acceptance of vaccines is going to be very spotty. I think 50% is highly optimistic.
Are there studies from countries with mask wearing pre-Covid that show it reduces the spread of flu and colds?
yes there are of limited quality (mostly from Japan). other studies done in hospital personnel threw some cold water on this idea. but overall i would say the evidence is somewhat supportive
Perhaps the willingness to be vaccinated with a 90% effective vaccine is less than for a 70% effective vaccine because some people figure that if the vaccine is 90% effective, they can let everyone else get vaccinated and still be protected by the herd effect. In other words, a very effective vaccine might encourage free riders.
Or, if it is a more powerful vaccine, it is possible that its unwanted side effects may also be more powerful.
Possible. But not very likely.
Or those who are skeptical about government and/or corporate announcements might be more so about a 90% claim than a 75% claim.
I hope there will be a “existing biotechnology” competitor vaccine available at the time this “new unproven biotechnology” mRNA Pfizer vaccine becomes available in USA.
Any biological/medical Pro like Ignacio can comment on this mRNA vaccine? It just seems inprudent & unscientific to test such an new biotechnology on a mass scale, e.g 70% of USians or humans globally to take it. Is there a biomedical reason why a COVID vaccine could not be made with whatever the existing vaccine technology that is used for Polio, MMR, HPV, flu, etc?
Earnest question, please don’t shoot the messenger as an anti-vaxxer
I’m not an expert, but I don’t know of a reason that existing technology can’t make a COVID vaccine, I think that they are trying. But they have tried many times to make a good vaccine for various coronavirus and haven’t succeseded yet. They either haven’t worked well enough, or had terrible, sometimes deadly side effects. So, unfortunately, all coronavirus vaccine technology is unproven and carries real risk.
Not an anti-vaxxer or biotech, I’m a nurse. I am extremely unnerved that there are zero vaccines being developed in the US with the tried and true, old-fashioned but proven, whole killed, or attenuated method. We have never had long-term experience with an mRNA, or a virus vector vaccine – there is a reason the fastest vaccine development was four years (mumps) – side effects can take years to emerge, witness the initial rollout of the measles whole killed vaccine in 1963 that ended up giving children and adults a measles-type illness after exposure to live virus. We now have the attenuated measles vaccine. And the issue of NO SURVEILLANCE, such as weekly swabs for volunteers, for asymptomatic infection is outrageous. The Coronavac vaccine current being trialed in Brazil (I know, Bolsonaro, but the Butantan Institute is world-renowned and reliable) is produced by the Chinese and it is a whole killed virus vaccine. At this point, in the midst of huge Phase 3 trials it looks to be the safest with fewest and mildest adverse reactions. I would not take a vaccine with an unproven, untested genetic technology. Why are there no traditional vaccines being produced here??Not only that, the vector and genetic vaccines only target the spike protein, which may render them ineffective if the virus mutates sufficiently
mRNA vaccines are genetic dead ends. Should not be high risk. More problems tend to arise with live attenuated vaccines (basically a weakened strain of virus which is nonpathogenic but confers immunity) which can replicate, and potentially regain virulence.
RNA viruses constantly mutate. I don’t feel confident that we can use the same language developed to talk about the behavior of DNA-based viruses and apply it to a virus like Covid. Our past successes with vaccines have been dependent on the logical, roughly-predictable mechanisms for replication in a virus that RNA-based viruses lack. At least that’s my understanding so far. Therefore, I’ll be looking at all of these rapidly developed vaccines with suspicion. How effective can they be and for how long? I need to hear something new in the language of this vaccine development that addresses the sloppy (?) fast changing nature of RNA. Instead it sounds corporate, that is to say short-sighted and probably profit driven. The potential market is 8 billion people. Like the “science” behind every zombie movie where the narrator tells the audience the scientists meant well, but alas…
We’ve decided we’ll have injected whatever vaccine passes Laurie Garrett’s sniff test. Laurie has a deeply discerning nose.
SARS-Cov-2 is different from other RNA viruses because it has a proofreader to prevent mistakes during replication. Although some mistakes are let through this occurs at a much lower rate than the typical RNA virus leading to a lower mutation rate.
This proofreading can be an advantage for the virus when trying to develop anti-virals but this could also be a disadvantage if (yet to be proven) a vaccine is successful.
This article Slipping past the proofreader although about Remdesivir explains the differences SARS-Cov-2 has with other RNA viruses.
Thank you, Troy. I’ll read it.
Retroviruses have high error rates. Other RNA viruses less so. I do not see how RNApol proof-reading, and therefore a low mutation rate, would be a disadvantage to vaccine development. As with artillery, it is usually easier to hit an object which is stationary.
I agree there is no medical education ongoing in the US. Being around medical people quite a bit, I’m constantly reminded that under normal circumstances it takes roughly five years to get a reliable vaccine on the market. We need to understand that this is a long term problem. In this case people are correct in their suspicions, given this is a novel virus, and we are constantly learning more critical aspects of this bug.
Inasmuch as certain people are running at “warp speed”, they will overlook important features, and are bound to run into some interesting problems.
One real aspect is that societally the stakes are so very high in a failing economic and political system, that our rulers and propagandists are grasping at anything to maintain their credibility. We are victims of instant solutions and politicized information, and therefore will constantly be whip-sawed with “new findings”.
Meanwhile, at a local level, I am anecdotally finding mask skeptics converting rather quickly after the bug hits them very closely in the “Great Midwest”. It’s no wonder that New Yorkers and Washington staters are so much more on top of this problem.
Typhoid Mary worked as a cook spreading typhoid, a bacterial infection due to a specific type of Salmonella, through the food she prepared. We have thousands of Corona-Marys chasing about spreading the Corona virus through breathing, talking, laughing, coughing, sneezing, yelling, and singing. Am I wrong in thinking that identifying these super spreaders and finding ways to stop them from spreading Corona virus is more important than finding a quick fix vaccine with dubious provenance and vaccinating the entire population — assuming that were possible? If our Medical Industrial Complex cannot even come up with an inexpensive and reliable test for the Corona virus why should we trust their warp speed high profits vaccine development? The Corona-Marys should be identified through a widespread program of testing using an inexpensive and reliable test for the Corona virus combined with effective ‘old-school’ [skip the apps!] contact tracing and those Corona-Marys should be the first to get vaccinated if a safe and effective vaccine is developed.
I think we in the US would all be better off if wearing masks in public places became the norm as it is in the Orient. Forget the Corona virus — the common cold didn’t disappear; other flus are still around and very unpleasant; sick leave in the US … left to provide a small kick to past profits; AND the Corona pandemic was just a test — Society has fostered conditions increasing the chances for developing a much more dangerous disease. Besides I like the idea of making face recognition a more difficult problem for our keepers.
Is it wrong to wonder whether efforts should be made to identify better mask filtering materials and mask designs? Many cloth masks have pockets for inserting filters. Would it be too much to ask for a standard design for those pockets so they might best fit a standard filter insert?
And tose super spreaders, would tey be sharin’ t’same economic class as Mary? And t’stigma once diagnosed? Are you okay wit tat?
(A Larry the Cable Guy apology to Gaelic speakers everywhere)
Or will they be the jet setters that won’t keep their butts still?
My sneaking suspicion is the super spreaders are healthcare workers and children (and now college students).
Would you prefer ‘Typhoid Tony’ — for Tony Labella? It does have a nice alliteration, but none of the currency of ‘Typhoid Mary’. As for the economic class — it might be difficult to find a high economic class person involved in the hands on preparation of food for many others. Salmonella bacteria do spread differently than Corona.
I think whatever stigma attaches to the term should fall on the heads of our public health authorities who seem to have only recently rediscovered asymptomatic disease carriers.
We can house them all in giant soccer stadiums! Wait. Has that been done before?
We could give them first shot at a safe, efficient vaccine.
I also believe it might be a good idea to try and figure out how the virus infects them without causing symptoms. Other viruses might use a similar method.
If we need giant soccer or football stadiums to house all the asymptomatic Corona carriers we may have quite a problem to deal with.
“our Medical Industrial Complex cannot even come up with an inexpensive and reliable test for the Corona virus why should we trust their warp speed high profits vaccine development?”
1000000x agreement.
When I first saw the title of this post I thought it might be about something slightly different. I have an acquaintance who lives in Liverpool in the UK where mass testing of the whole city is taking place. She is reluctant to go for the test because the queuing for the test is badly organized and people are getting the Virus whilst queuing up. It struck me that queues for vaccination might be mass spreader events.
There is another way of looking at the possibility of vaccinated people behaving recklessly. While admittedly vaccination might increase reckless selfish behavior the pool of selfish people will diminish with time. Those who have not had the virus are likely to have a higher proportion of people who take precautions and want to protect others. Another factor is that as more people know relatives or friends who have had a hard time with the virus their attitudes will change. Once we have more images of bodies stacked up in temporary morgues and the family stories behind those people attitudes will change as well.
I am starting to think herd immunity is closer than a vaccine for the US anyway. On the 12 of October there were 48,016 new cases in the US and today there are 142,856 which means that case are trebling every month. At this rate in 3 months time 4 million people will have the virus and you may be getting near herd immunity in 6 months.
I thought the concept of herd immunity had everything to do with vaccines?
The corona type viruses aren’t like the chicken pox – once you get it, you’re immune. People have failed to understand that.
“How big a problem this might be is hard to say, because we don’t know for sure if immunized people are capable of shedding infectious virus.”
This is an example of the type of information that makes it difficult or me to take to heart any of their claims about the vaccine.
But I am skeptical of this rush job most of all.
Interesting radio piece on BBC yesterday, starting at 6:49–interview with a Dr. Poland (sp?) who is apparently head of vaccine research at Mayo. He gets super specific about what it is Pfizer is claiming with this 90% effective.
https://www.bbc.co.uk/programmes/w3cszccs
He points out: a).. it is a press release, not a scientific paper; b). it is a very early and narrow sliver of data, namely the first seven days after the second dose of vaccine, and b). only for prevention of mild/moderate Covid–so not asymptomatic, not severe Covid, and c). tells us nothing about vaccine effect–if any– on transmissability, nor d). what the results might have been if we were not already social distancing, masking, etc.
At the end of the piece (at 24;40) there is also an interesting conversation with another person about what standards the second vaccine to come along will have to meet for US approval–it will have to be better, not than placebo (or doing nothing), as the first has to be, but better than the first approved vaccine’s 90%? If so, first approved would seem to gain a monopoly?
The whole thing is worth a listen, in my opinion.
For most healthy young people, the SARS-CoV-2 virus functions as a vaccine. They get mild to no symptoms and pick up some sort of immunity against reinfection. As I understand it, this Pfizer vaccine is only tested on healthy people. I wonder how well it would perform in a comparison to the virus itself? For example intentionally giving a minimal viral load of SARS-CoV-2 and see what the reaction is.
If the Pfizer vaccine is only tested on healthy (and presumably younger) people, surely further tests should now be conducted on elderly and/or unhealthy people to see how effective the vaccine is? Only if it is safe and works with this demographic would the vaccine show itself to be more effective than just using the SARS-CoV-2 virus itself.
Kasia,
It is a virus. It is pathogenic, may get you sick, may leave you with long term sequelae (lung, heart damage possibly) and it may kill you. That does not sound like a vaccine to me.
Diversity in clinical studies is important and there have been improvements on that front. A vaccine that is only effective in healthy young people would be less than ideal. However, considering that young people can also spread viruses, immunizing them would still be beneficial. If you can’t get it you can’t spread it.
And this all assumes the vaccine won’t go bad in warm fridges at the last stop, and actually be innefective.
for more scientific information about clinical endpoints for vaccine trials here is the best article i have found
https://www.acpjournals.org/doi/10.7326/M20-6169