The mutations that help the virus spread and evade immune responses have arisen independently in multiple places. Combined with waning immunity, these factors underscore the challenge before the world: Populations may still be vulnerable to disaster scenarios just when things seem to be getting better. It’s not yet known how many of the people currently infected in Manaus have previously recovered from COVID-19. Early data suggest that the P.1 variant is now dominant in the city, but this does not mean the variant will take over everywhere. Each place and population is unique, and susceptibility will vary based on which variants have already spread. Still, the virus’s capacity to cause such a deadly second surge in Brazil suggests a dangerous evolutionary potential.
As the virus evolves, the threat is not encapsulated by any single variant. New, dangerous variants are all but inevitable when there are extremely high levels of transmission of the virus. As more people gain immunity, the selective pressure on the virus will favor the variants that can most effectively evade immune responses. Whether the Brazil variant manages to widely evade human immune responses, or whether some future variant does, the basic nature of evolutionary biology means that the virus should be expected to evolve in ways that circumvent defense mechanisms. Evidence that it is already doing so has been clear in the latest vaccine trial data.
The solution, then, depends on vaccination. The immune response that the vaccines create is generally more robust than the immune response we get after being infected by a virus, and should buy a population more protected time than would a surge in exposure to the virus. Wealthy countries have time to avoid a fate like Brazil’s through immediate, efficient vaccination. In most places, however, this is not close to happening. And as of last week, only one of the world’s 29 poorest countries had vaccinated anyone at all. A study in the journal BMJ estimated that vaccines will not be available to more than a fifth of the world’s population until 2022.
The coronavirus’s constantly evolving nature is a stark reminder that the entire world is in this crisis together. Vaccine distribution is more than just an issue of justice or morality. Ensuring that every human is vaccinated is in everyone’s interest, as global distribution of vaccines is the most effective way to drive down the virus’s capacity to replicate and evolve. The key will be bringing down the global rates of transmission as quickly as possible—not getting any single country to 100 percent vaccination while dozens of countries roil.
“It is truly confounding that wealthier nations think that hoarding vaccines is the way to protect their citizens from a global pandemic that doesn’t respect borders,” the global-health researcher Marine Buissonnière said in a Physicians for Human Rights meeting on Friday. As the virus currently surges across Africa, some 2.5 million health-care workers are unvaccinated. “Clearly, the failure to address vaccine allocation based on health and epidemiological needs, rather than national interest, is now promising to have a dire impact on the world’s ability to achieve rapid, global control of COVID,” Buissonnière said.