COVID-19 Vaccine: I think it will happen, but it won't happen as fast as we'd like
There's a lot of excitement about a vaccine that would protect against SARS-CoV2, the novel coronavirus that causes COVID-19. There are even trials going on in China, the UK, and the US. Although we've never produced a vaccine in less than four years, many think that the multitude of labs working on different vaccine formulations (over 100), the rapid genomic sequencing, and the relative genetic stability of this virus makes it a good candidate for a vaccine.
But predictions that we'll have a vaccine by fall are unrealistically optimistic - and we need to have effective contingency planning that is not dependent on an early vaccine.
Here are reasons why it takes a long time to get to "herd immunity" through vaccination:
The vaccine must be shown to be safe before we use it. This is not a small issue; the swine flu vaccine (1976) was associated with Guillain Barre Syndrome, progressive paralysis. Dengue fever vaccine is associated with protection only in those who have had infection before - and can make cases more severe if given to those who have never had the disease.
The vaccine must be shown to be effective. We've been hoping for a vaccine against HIV since the 1980s - but we're still waiting. People might need more than one shot of a vaccine for protection, and protection might wane after a short time requiring many booster shots
The vaccine must be mass-produced. The US uses 140 million eggs each year to produce influenza vaccine. We don't know how tricky the mass manufacture of a coronavirus vaccine will be, but we are not going to manufacture 8 or 16 billion doses in a matter of weeks. Even manufacturing the vaccine for just the US market will be daunting, and our world will not be safe as long as there are unvaccinated people elsewhere
People have to get the vaccine. It's estimated that only 47% of adults got influenza shots during the 2018-19 season. (The 2019-20 data is not yet available.) Only 64% of those surveyed reported that they would definitely get a coronavirus vaccination, and 14% said they would refuse. Some had hoped that this pandemic would make more people enthusiastic about life-saving vaccines. That might still happen, but right now there is a crisis of decreased pediatric vaccinations. The week of April 5, a pediatric electronic medical record company reported that "measles, mumps and rubella shots dropped by 50 percent; diphtheria and whooping cough shots by 42 percent; and HPV vaccines by 73 percent."
There have been some press reports about experts who doubt there will ever be a COVID-19 immunization. Here is a report from Business Insider and one from CNN. Skeptics point out that there has never been a coronavirus vaccine in the past, and that we have no proof that there is active immunity after infection. On the positive side, SARS-CoV-2 appears to be have little "genetic drift," making it more likely that a vaccine would not have to be frequently formulated. There is some evidence that survivors of two other coronaviruses (SARS and MERS) have short term immunity. Immunity to common cold coronaviruses, though, is often under a year.
I believe there will be a vaccine, though I'm skeptical that it will be ready in less than a year, and the challenge of immunizing 330 million in the US alone is enormous.