Study Shows Previous Omicron Infection Is Most Protective Against BA
A study in The Lancet Infectious Diseases shows that prior Omicron BA.1 infection was the most protective factor against BA.2 infection (associated with a 72% risk reduction) and provided greater protection than primary infection with pre-Omicron SARS-CoV-2 (38%) or three doses of an mRNA vaccine in people with no previous infection (46%).
The test-negative case-control study involved health professionals from Quebec to compare those who tested positive for SARS-CoV-2 during the period of Omicron BA.2 dominance, from March 27 to June 4, 2022, with health professionals who received a test negative. negative test in the same period.
The primary COVID-19 infection had to occur at least 30 days before the study period, with pre-Omicron infections occurring between February 20, 2020 and November 27, 2021. Omicron BA.1 attribution was given for all cases between December 26, 2021 and March 26, 2022. A total of 37,732 presumed Omicron BA.2 cases were compared with 73,507 randomly selected controls.
The authors said that of the cases, 1,159 (3.1%) had a primary infection in combination with two mRNA vaccine doses, and 1,436 (3.8%) had a primary infection and three vaccine doses. Of the controls, 687 (10.9%) had a primary infection combined with two vaccine doses, and 821 (13.4%) had a primary infection and three vaccine doses.
Hybrid immunity to BA.1 infection plus two or three mRNA vaccine doses increased efficacy to 96% for longer than 5 months. Notably, a third vaccine dose did not improve that hybrid protection.
“These data provide an immunological context for the importance of hybrid immunity in controlling the current peaks induced by the BA.2.12.1, BA.4 and BA.5 subvariants in populations with high vaccination frequencies and BA.1 or BA.2 infection,” writes David Hui, MD, of the Chinese University of Hong Kong, commenting on the study. “Another important factor in reducing infection risk is heterologous booster vaccination with different platforms to maximize the scope of vaccine-induced immunity, especially in countries that primarily use an inactivated vaccine.”
Sep 21 Lancet Infect Dis study and commentary
Agreement paves the way for greater global access to Paxlovid
Pfizer announced today that it has signed an agreement with the Global Fund to deliver up to 6 million Paxlovid courses to 132 low- and middle-income countries to help treat COVID-19.
Countries will have access to the drug through the Global Fund’s existing pandemic response mechanism, which has been used to provide grants for tests, treatments, personal protective equipment and other elements for strengthening health systems.
In a statement, Pfizer said it expects delivery to begin this year, based on regulatory approval and demand from the country. Countries can purchase supplies through tiered pricing at Pfizer’s non-profit rate. Albert Bourla, Pfizer’s chief executive officer, said the engagement with the Global Fund is promoting equitable access to treatment for high-risk groups in low- and middle-income countries. The company also said the agreement builds on previous efforts to facilitate access.
In U.S. developments, an official with the Food and Drug Administration this week said updated COVID boosters for children ages 5 to 11 will be approved in the coming weeks, according to ABC News. Peter Marks, MD, PhD, who directs the FDA’s Center for Biologics Evaluation and Research, spoke at an event with the COVID-19 Vaccine Education and Equity Project. Earlier this month, the new booster was approved for emergency use in people as young as 12 years old.
Sep 22 Pfizer Statement
Sep 21. ABC News story