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Covid-19 Vaccine Candidates (wikipedia.org)
53 points by flipchart on May 20, 2020 | hide | past | favorite | 63 comments

Nature had a nice graphic showing the different approaches being taken: https://www.nature.com/articles/d41586-020-01221-y

Twelve candidates in clinical trials according to the table. That sounds like a lot, but I have no idea how that number compares to other vaccines. Is this a typical number, or is it high/low?

From my perspective it is quite a number all at once. Usually it is a lot less (one or two candidates, AFAICS).

It seems like a lot, but under the circumstances that shouldn't be surprising.

Has there ever been an attempt to develop a vaccine against SARS or MERS? If so, what happened? Did it fail or was is just not needed anymore?

Late stage vaccine trials are conducted by vaccinating a bunch of people and then seeing how many get infected versus a control group. So it's not just a matter of "not needed"; the trials simply couldn't be performed without an active outbreak of the disease. There was a lot of promising early-stage development.

SARS had several canditate vaccines in human trials. These were all shelved once it was erradicated.

MERS vaccine development is ongoing, with promising canditates in human trials.

Wikipedia has a brief summary of prior work on vaccines against other coronaviruses, including SARS and MERS.


That's how these got developed so fast, take a MERS vaccine and update it.

Click the wikipedia article, and click to the History section.

From my understanding, they were started, but then both SARS and MERS burned out so fast that they couldn’t find enough candidates to test the vaccines by the time they got to trials.

Given the ages and health conditions of the dead, what is the chance that a vaccine will do any good to them? Remember that the flu vaccine is of very dubious effectiveness on those aged 65+.

Of course, vaccinating the whole population might render those groups less likely to be infected (because of herd immunity) but still, it will involve vaccinating populations which have little risk from the disease with a vaccine that has been fast-tracked through the approval process.

This situation is a disaster.

Remember that the flu vaccine is of very dubious effectiveness on those aged 65+

The CDC still recommends vaccines for the elderly:

Because of age-related changes in their immune systems, people 65 years and older may not respond as well to vaccination as younger people. Although immune responses may be lower in the elderly, studies have consistently found that flu vaccine has been effective in reducing the chance of medical visits and hospitalizations associated with flu.

Source: https://www.cdc.gov/flu/highrisk/65over.htm

They are still only ~50% effective.


There's a vast gulf between "~50% effective" and "very dubious effectiveness"

There are plenty of people under 65 who are being killed or suffering major medical issues due to COVID-19. A friend of mine is in great health, 40, and spent 6 days in the ICU and may never recover fully (lung function damage). A vaccine would be great.

As I understand it its a very small proportion of people that age.

Roughly 25% of deaths in the US are people under 65. I think those people and their families would see the value in a vaccine.

Question: if the virus completely dissapears in a few months, like other SARS variant, should we vaccinate the world population ?

Obviously not, but why would it do that? It's already spread in a way that none of the other SARS variants have, which invalidates that part of the analogy.

Global natural herd immunity could suppress the disease cases to next to nothing. The problem is there's a very high price to pay before we get there.

The parent said "like other SARS variant," they were not talking about herd immunity. MERS and SARS-1 did not get anywhere near herd immunity, they were simply too slow-spreading to catch on. (I'm not sure if MERS can spread human-to-human at all, and SARS-1 was relatively slow.)

It's highly likely a vaccine is the only thing that will work.

The virus would need to spread a lot faster globally than it has so far to accomplish that mass herd immunity before the people hit in the first months lose immunity and become susceptible again. At the rate it's going, the virus will still be raging in numerous parts of the world toward the last quarter of the year, just in time for influenza season to start up again in the northern hemisphere.

It's the scenario where you persistently have cases in many parts of the world that are able to reinfect locations that have built up herd immunity previously (and then lost that immunity), so the virus just keeps going around the planet and you can't fully get rid of it. Whack-a-mole style.

Perhaps very long-lasting travel lock-downs could isolate that risk somewhat, however I'm skeptical about that working effectively as the world is still super connected in terms of supply chains and transiting goods (and the people that move them), mixed with the nature of this virus (specifically how easy it is to spread).

why is the virus already disappearing from all over europe ? If it's because of containment then it will reappear very soon since everybody here is starting to get out again.

We don't know why viruses appear and disappear, but they do all the time, every year.

First of all, we know why viruses disappear.

Secondly, we know why it’s disappearing - it’s clearly associated with containment measures.

Do you have articles explaining that ? I'm not a biologist, so i'm only reporting what i've heard and read from professionals working on the subject, but maybe you've got better sources.

Serious question, how could it disappear? It seems like as long as there are people close enough to infect, it will infect them. There are cases in warm environments. What am I missing?

Previous pandemics (most notably 1918 Spanish flu) have “disappeared” in the sense that they had either exhausted the pool of hosts and had no natural reservoir with which to fall back on or they mutated to become less deadly or less symptomatic.

The Spanish flu strain (H1N1) circulated as the common flu until 1957 when it was replaced by Asian flu in 1957 (H2N2). However, it reappeared briefly as the Russian flu in 1977.

And then reappeared as Swine flu in 2009.

How does mutating eradicate the non-mutated individuals?

In the Plauge Inc videogame, you can upgrade your virus globally by unlocking mutations. I think that might be where the popular misconception about mutations instantly weakening the virus on a global scale come from. In real life that can happen, but only in situations where it sits around in the population for years, so that it has had several "go-rounds" to sieve the best genotypes from the worst.

My personal theory is that lethal mutations or the ones that cause severe symptoms get detected and isolated where possible, while the mutations that cause only mild or no symptoms can continue spreading silently without anyone noticing. If both create the same immunity, the non lethal mutations will win. If this theory holds, testing only if a person is showing symptoms would be the right thing to do. Filter the dangerous mutations, let the other ones spread.

A mutated virus that spreads faster gives immunity to the hosts it infects from the ones that spread slower. The hope is that the more transmissible strain is also less lethal.

Not in a few months.

>What am I missing?


Accepting that we know still very little about this pandemic and how it will play out is the only perspective that is not delusional.

That was my point: it is delusional to believe that the virus will "completely disappear in a few months".

User "Touche" asked what he is missing to be convinced that the virus will disappear: he is missing delusion.

Is there any trend or metric we can monitor for sign of that? Like, average time required in ICU shortening, which may mean virus is weakening?

One thing would be seeing a significant mutation appearing in the wild, and noticing that people with that mitation have less symptoms.

For covid, the mutations were minimal, which makes sense - the virus’ construction make it unlikely to mutate (unlike flu).

That wouldn't make the virus disappear though, it would make it less severe. Which is good! Hopefully that happens. That it mutates to the point of being significantly less deadly before a vaccine seems unlikely to me.

We're well past the stage where the virus may 'disappear'. Look at MERS[0] (which is still around) and SARS[1]. Compare that to COVID-19 [2].

I'd say the case for vaccination is pretty obvious, even if there is a lull in cases. Seasonal COVID outbreaks don't sound fun.

[0] https://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Wo...

[1] https://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/20...

[2] https://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/To...

To be clear, MERS-CoV has not had sustained human-to-human transmission as of yet, rather repeated, smaller transmission pockets. Also, dromedary camels carry it and repeatedly introduce it into the human population.

Without the testing capacity to know that it actually did disappear, the question seems moot.

Maybe in one specific scenario, though. If the vaccine seems to have negative effects, and if the disease seems to have petered out on its own, then we could manufacture enough vaccine, then be ready to give it out if/when another outbreak happens.

If it did disappear, sure.

But it won't. Way too many infected all over the globe now, eradication is impossible without a vaccine. Either it will eventually infect the entire world, or we'll vaccinate against it. Those are the only two options at this point.

Even if an entire nation managed to eradicate it via distancing, it would only take a single carrier arriving by any means from another country to initiate a second wave and restart the clock.

Edit: I'm not one to engage in meta, but seriously, what the fuck is with the downvotes? Every word of what I said is casually verifiable with a quick google search and is not at all controversial. There is absolutely no way to eradicate SARS-CoV-2 without global immunity due to its exceptionally high R0 combined with the fact that it's already present all over the globe. The only two ways to achieve global immunity is if everyone gets infected and develops immunity, or everyone is vaccinated. Someone who's hitting downvote, please comment and explain.

There is another way of looking at this.

If an area has contained it once, they have to do it again. They have to try. They are not immune.

If the US decides to go it alone on the herd immunity approach, because they are incapable of making any other approach work, and all other countries reduce the infection rate to close to zero over the summer with the lockdown approach, that US travel ban aint getting lifted.

Most countries have attempted lockdown, opening up as and when their health services are able to cope.

If US citizens were immune but contagious, US citizens would only be free to travel within US borders.

Could end up with Lockdown, branded as freedom.

In that light it makes sense to what ever the rest of the world does.

Green zones and red zones with strict measures to prevent case importation are also an option.

A few countries/regions currently have close-to-zero new cases and may become green zones where economic and other activities will mostly resume to normal.

Measures that have been used include quarantine and follow-up contact tracing.

Third option: we fight it with drugs and we prevent / reduce hospitalizations, and it becomes a disease like every other.

The obvious comparison is tuberculosis, where vaccination (albeit not universal vaccination) is a critical component of our control measures. Even if we find a strongly effective treatment, which I agree there's reason for optimism on, we'll still want a vaccine.

Yeah, lockdown == prevent. ICU == treat. At the moment thats all we have

Many doctors are actually experimenting different treatments, even handling in the ICU has shifted compared to two months ago.

The problem is that most of the pharmacological evidence is sparse and anecdotal at worst (except for remedisivir, and now lopinavir/ritonavir/ribavirin/interferon beta). Trials are ongoing and should at least give better answers, or hints.

Protocols change among countries or even across hospitals, so it's kind of hard to figure out which treatment is best. There's a lot of road to cover to come to proper treatments, but if we are to believe case reports, it is undoubtedly much better than when the pandemic started hitting the West.

Vaccines will help with that, like with the flu.

If a useful treatment shows up, that would certainly be an option, though vaccination would be preferable if feasible.

No, that's the first option - it will eventually infect the whole world no matter how much you improve outcomes or slow it down. Unmitigated R0 of SARS-CoV-2 is extremely high, we can't keep it contained with spreaders all over the globe creating micro clusters every day. I didn't say it'll kill the whole world, just infect.

Many countries have already brought their case rates down to almost 0, and every single one that attempted to resume economic activity saw the case rates spike again, with many now re-introducing distancing measures again. This genie is not going back into the bottle.

The first option is actually potentially more viable on a reasonable timeline than vaccination, especially if we manage to find some kind of effective therapeutics which reduce the ICU and mortality rates.

There is however a potential issue, which is based on SARS data, immunity in recovered individuals only lasts 1-2 years. So unless there's a concerted effort to eradicate via immunisation, there's a measurable risk that SARS-CoV-2 will become a seasonal repeating wave like Influenza.

I have no hard data (and I don't think anyone has, at this point), but eradication is IMO going to be tricky even if we have a very potent vaccine, at least looking at how much it took for chicken pox.

Oh absolutely. Eradicating this thing via vaccination any time in the next 24 months will take a completely unprecedented feat of worldwide collaboration.

But I'm optimistic, the current situation has everyone focused on the issue. Except Trump trying to get some special deals for early access or whatever the fuck it is that he's doing.

Any country that physically manufactures vaccine doses isn't going to allow many exports until they have a sufficient domestic supply. That's not just a Trump thing.

That's precisely why many vaccine producers are seeking partnership and starting manufacturing at risk.

As an example, Moderna teamed up with Lonza (and also got a big grant from BARDA). Oxford / Vaccitech has deals with Astra Zeneca, Merck, and a few other manufacturers.

I think if we can safely eradicate it, yes, but it's spreading much faster than the other SARS variant or Ebola. Maybe in a few years? Smallpox was eradicated in 1977, but we hunted it down mercilessly before we stopped vaccinating.

> completely dissapears

Seems unlikely.

sars-cov-2 has proven to be much more difficult to contain than sars-cov-1.

Even if it was contained and was greatly reduced, we'd face a substantial risk of another wave. Supposing we had an effective, safe vaccine with reasonable cost, balancing the risk and cost of vaccinating vs not vaccinating, I'm pretty sure we'd want to vaccinate. The last thing we'd want is another global shutdown in, e.g. 2022.

In any case, this would be a wonderful choice to face, since it assumes covid-19 is gone and a safe, effective vaccine with reasonable cost exists.

The SARS-1 outbreak lasted about two years.

But if it _does_ vanish in a few months (sadly, this doesn't seem plausible), it would probably make sense to produce and stockpile a vaccine, if a viable one is found, but not actually vaccinate unless it reappears.

Did it realy last 2 years? This graphic indicates that it lasted only for 4 months, then is was more or less over:


There were periodic outbreaks into 2004. Given how much more infectious this disease is, I don't think we'd call it 'over' if outbreaks were still occurring.

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