P.1 variant in Manaus, Brazil linked with COVID resurgence now despite reportedly crossing “theoretical herd immunity threshold” in October

When will new vaccines include the P.1. variant?

The resurging epidemic in the northern Brazil city of Manaus, Amazonas state, is another of the many cautionary lessons in humility this pandemic has shown the world over the past 13+ months.  On Jan. 26 the Pan American Health Organization reported that the P.1 variant first found in Manaus was not detected from March through November, but by the escalating epidemic in January 2021 it was found in 85% of patients (41/48 viruses), up from 52% in December.

In a humbling juxtaposition to the ongoing epidemic that has even exhausted hospital supplies of oxygen in Manaus, a recent paper in Science  Jan. 15 (online Dec. 8), titled “Three-quarters attack rate of SARS-CoV-2 in the Brazilian Amazon during a largely unmitigated epidemic,” reported: “Our data show that >70% of the population had been infected in Manaus about 7 months after the virus first arrived in the city. This is above the theoretical herd immunity threshold. However, prior infection may not confer long-lasting immunity . . . Manaus represents a “sentinel” population, giving us a data-based indication of what may happen if SARS-CoV-2 is allowed to spread largely unmitigated.” Of note, the attack rate for SARS-CoV-2 was estimated to be "76% in October."

On Jan. 27, four potential explanations for this juxtaposition of apparent herd immunity being followed within months by another severe epidemic in Manaus, was discussed in a paper in the Lancet, titled “Resurgence of COVID-19 in Manaus, Brazil despite high seroprevalence.”

These “four non-mutually exclusive possible explanations” are: (1) the population may have not have really achieved herd immunity; (2) immunity from the initial wave of infections that peaked in late April may have waned; (3) the new lineages P.1 and B.1.1.1.7 circulating in Brazil “might evade immunity generated in response to previous infection”; (4) These P.1, B.1.1.7 “lineages” (aka “variants”) might have higher “inherent transmissibility” than pre-existing virus lineages in Manaus.

I agree with the crucial point by the authors in their discussion: “Determining the efficacy of existing COVID-19 vaccines against variants in the P.1. lineage and other lineages with potential immune escape variants is also crucial.”

Given the similarity of P.1 to the 501Y.V2 (B.1.351) variant first found in South Africa, I anticipate the urgent need for bivalent or trivalent vaccines that include this P.1 variant.