Omicron subvariants linked to reinfections

A new study based on COVID-19 patients in France shows high reinfection rates among people with different Omicron subvariants, including BA.1, BA.2, and BA.5. The study is published as a research letter in Emerging Infectious Diseases.

The research group conducting this study, from Aix Marseille University, previously found reinfection rates were 6-fold higher during the Omicron surge than in previous variant surges. In this study, the authors used a computerized alert system that identified positive case samples with primary Omicron BA.1 or BA.2 subvariant infections followed by reinfection with any Omicron subvariant.

They found 188 (0.7%) cases of reinfection out of 27,972 patient samples that tested positive for Omicron from Nov 28, 2021, to Jul 22, 2022. Of the 188 cases, 181 were first infected with the Omicron BA.1 subvariant. Of those, 82 patients were reinfected with Omicron BA.2, 14 were infected with Omicron BA.4, 84 with Omicron BA.5, and 1 with a BA.1 and BA.2 recombinant subvariant (XAC recombinant lineage).

The median age of patients was 32, and 70% were women. Time between two infections was less than 90 days for 50 patients (26.6%) and less than 60 days for 28 patients (14.9%).

“Our findings indicate that the time between confirmed primary infections and reinfections with different Omicron subvariants is frequently shorter than the 90-day definition of reinfections used by the US Centers for Disease Control and Prevention [CDC],” the authors concluded. “Furthermore, the time can be shorter than the 60-day definition of reinfections used by the European Centre for Disease Prevention and Control.”
Sep 23 Emerg Infect Dis study


Pfizer/BioNTech asks FDA to authorize bivalent COVID booster for kids

Pfizer and BioNTech have asked the US Food and Drug Administration (FDA) to authorize a bivalent COVID-19 booster for kids ages 5 to 11. The booster, already approved for adults, is meant to better protect against Omicron variants of the virus.

Moderna has also submitted a request for approval to the FDA of their Omicron booster for kids ages 12 to 17 and kids 6 to 11. Only 4.4 million adult doses of the bivalent vaccines have been administered in the United States.

The 7-day average of new daily COVID-19 cases is 50,749, with 398 daily deaths, according to the Washington Post tracker. In the past week, new daily cases fell 11%, hospitalizations fell 5%, and deaths fell 3%.

Late last week, the CDC published new guidance that says hospitals and nursing homes in counties with low COVID-19 transmission don’t have to require patients or staff to wear masks, CBS News reported.
Sep 26 FDA booster Reuters story
Sep 23 CDC guidance
Sep 23 CBS story


Vaccines protected pregnant women against severe COVID for 3 months

Pregnant women who received two or three doses of an mRNA COVID-19 vaccine were well protected against Delta- and Omicron-related hospitalization and emergency department (ED) and urgent care (UC) visits for more than 3 months, but protection appeared to wane to zero by 4 months, shows a US test-negative case-control study published today in JAMA Network Open.

The CDC COVID-19 Emergency Response Team led the study of 975 hospitalizations and 4,517 ED/UC visits by pregnant women for any cause from June 2021 to June 2022, a period that spanned the predominance of the highly transmissible Delta and Omicron variants. Of the 975 hospitalizations, 34.3% were for confirmed COVID-19, compared with 19.6% of the 4,517 ED/UC visits.

The women were seen in a network of 306 hospitals and 164 ED/UC facilities in 10 states. They had received a second dose of the Pfizer/BioNTech or Moderna COVID-19 vaccine at least 14 days earlier or a third dose at least 7 days earlier or were unvaccinated.

During Delta, estimated VE against COVID-19 hospitalization was 99% for two doses after 14 to 149 days, 96% for two doses given at least 150 days before, and 97% for three doses after 7 to 119 days. Estimated VE against ED/UC visits was 84%, 75%, and 81%, respectively.

Amid Omicron, estimated VE against hospitalization was 86% for two doses after 14 to 149 days, 64% for two doses after at least 150 days (but the 95% confidence interval ranged below 0), 86% for three doses after 7 to 119 days, and −53% for three doses given at least 120 days before. Estimated VE against ED/UC visits was 3%, 42%, 79%, and -124%, respectively.

The authors noted that COVID-19 during pregnancy is linked to an elevated risk of hospitalization, intensive care unit (ICU) admission, preterm birth, and stillbirth. Yet, despite current guidance from the CDC and the American College of Obstetricians and Gynecologists, COVID-19 vaccine uptake remains low among pregnant women.

The researchers said that the results “suggest that mRNA vaccine administration during pregnancy does not alter vaccine performance despite immune differences between pregnant and nonpregnant people.”
Sep 26 JAMA Netw Open study

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