Dr. Marissa Carter has posted a new blog on the SARS-COVID-2 outbreak in Brazil and its implications for the rest of us. While it’s possible that “Phase 1” of COVID will end in a couple of months, it’s possible that, thanks to these new variants, Phase 2 of the pandemic will begin. And it’s possible that Pandemic Phase 2 will look a lot like the 1918 flu pandemic Phase 2, which was very lethal.
As Dr. Carter explains, scientists are evaluating the impact of the new viral strain in Manus, Brazil, a city that was demonstrated to have a very high rate of seroprevalence for COVID-19 as a result of widespread infection by the previous strain. However, the city has been severely impacted by this second COVID wave only about 8 months after the first, when there ought to have been a significant “herd immunity.” There are several possible explanations. The first is that the seroprevalence data was badly flawed in some way no one understands (in other words, there wasn’t as much immunity as it appeared). The second explanation is that because the attempted lockdown failed, people went about their lives as usual, increasing the impact of the new strain. A third possible explanation is that the new strains circulating in this part of Brazil (and starting to circulate in the USA)—known as P1 and P2—are more “aggressive” (meaning, more infectious and possibly more lethal).
Unfortunately, it is possible that what is being observed in Manus, Brazil is COVID-19re-infection. It so, it would mean that the immunity resulting from the older more “benign” strains doesn’t protect against subsequent exposure a few months later. In fact, there’s the awful possibility that prior infection could make things worse, as Dr. Carter discussed in a previous post about Antibody-Dependent Enhancement (ADE).
Also, Dr. Carter has posted an explanation of the “R0” with COVID-19.
It’s a fair question of whether this information (or perhaps I should say, these possibilities) have an impact on vaccination programs. I’d say “no.” It’s possible that the immunity won’t last as long as we hoped, and it’s possible that we will need additional vaccinations to protect from the new strains. However, the reason that infection is spreading is that no one has an immunity to these new strains. It’s the reason measles devastated the Native American population when they were first exposed to travelers from the Old World. Immunity is our only hope.