COVID-19 scan for September 22, 2022

The study shows that previous Omicron infection protects best against BA.2

A study in The Lancet Infectious Diseases shows that prior Omicron BA.1 infection was the best 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 without a previous infection (46%).

The negative test case-control study involved healthcare workers in Quebec to compare those who tested negative during the period of Omicron BA.2 dominance by 27 during the same period.

Primary COVID-19 infection had to have occurred at least 30 days prior to the study period, with pre-omicron infections occurring between February 20, 2020 and November 27, 2021. Omicron BA.1 assignment was awarded for all cases between December 26, 2021, and March 26, 2022. A total of 37,732 putative Omicron BA.2 cases were compared to 73,507 randomly selected controls.

The authors said that of the cases, 1,159 (3.1%) had a primary infection combined with two mRNA vaccine doses and 1,436 (3.8%) had a primary infection and three vaccine doses. Among controls, 687 (10.9%) had a primary infection combined with two doses of vaccine and 821 (13.4%) had a primary infection plus three doses of vaccine.

Hybrid immunity to BA.1 infection plus two or three doses of mRNA vaccine increased efficacy to 96% for more than 5 months. Notably, a third dose of vaccine did not improve this hybrid protection.

“These data provide an immunological context for the importance of hybrid immunity in addressing the current flare-ups caused by subvariants BA.2.12.1, BA.4 and BA.5 in populations with high vaccination frequency and BA.1 or BA.2 become infection,” writes David Hui, MD, of the Chinese University of Hong Kong, in a comment on the study. “Another important factor in reducing the risk of infection is heterologous booster vaccination using different platforms to maximize the breadth of vaccine-induced immunity, especially in countries that mainly use inactivated vaccines.”
21st September Lancet Infect Dis to learn and comment

Agreement paves the way for greater global access to Paxlovid

Pfizer announced today that it has signed an agreement with the Global Fund to provide up to 6 million Paxlovid courses to 132 low- and middle-income countries to support the treatment of COVID-19.

Countries will have access to the drug through the existing Global Fund Pandemic Response Mechanism, which has been used to provide grants for testing, treatment, personal protective equipment and other items to strengthen health care systems.

In a statement, Pfizer said it expects delivery to begin this year based on regulatory approval and country demand. Countries can purchase supplies through tiered pricing at Pfizer’s charitable rate. Albert Bourla, Pfizer’s chief executive officer, said the outreach to the Global Fund promotes equal access to treatments for high-risk groups in low- and middle-income countries. The company also said the agreement builds on previous efforts to ease access.

Regarding U.S. developments, a Food and Drug Administration official said this week that 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 released for emergency use by people aged 12 and over.
September 22 Statement by Pfizer
September 21 ABC News story