Signals of significantly increased vaccine breakthrough, decreased hospitalization rates, and less severe disease in patients with COVID-19 caused by the Omicron variant of SARS-CoV-2 in Houston, Texas

Abstract

Genetic variants of SARS-CoV-2 continue to dramatically alter the landscape of the COVID-19 pandemic. The recently described variant of concern designated Omicron (B.1.1.529) has rapidly spread worldwide and is now responsible for the majority of COVID-19 cases in many countries. Because Omicron was recognized very recently, many knowledge gaps exist about its epidemiology and clinical severity and disease course. A comprehensive genome sequencing study of SARS-CoV-2 in the Houston Methodist healthcare system identified 862 symptomatic patients with infections caused by Omicron from late November 2021 through December 18, 2021. Omicron very rapidly increased in only three weeks to cause 90% of all new COVID-19 cases. Compared to patients infected with either Alpha or Delta variants in our healthcare system, Omicron patients were significantly younger, had significantly increased vaccine breakthrough rates, and were significantly less likely to be hospitalized. Omicron patients required less intense respiratory support and had a shorter length of hospital stay, consistent with decreased disease severity. Although the number of Omicron patients we studied is relatively small, in the aggregate the data document the unusually rapid spread and increased occurrence of COVID-19 caused by the Omicron variant in metropolitan Houston, and provide information about disease character.

Boosting with Omicron-matched or historical mRNA vaccines increases neutralizing antibody responses and protection against B.1.1.529 infection in mice

“…These changes in the spike raise concerns for escape from protection by existing vaccines that target early pandemic spike proteins. Indeed, reduced serum neutralization of B.1.1.529 virus (Edara et al, 2021; Pajon et al, 2022) and large numbers of symptomatic breakthrough infections with B.1.1.529 have been reported in vaccinated individuals (Buchan et al, 2022; Christensen et al, 2022; Elliott et al, 2021).…”

Coronavirus Disease 2019 (COVID-19) Vaccine Boosting in Persons Already Protected by Natural or Vaccine-Induced Immunity

“…However, by this time it was known that this variant had a large number of mutations, including several on the spike protein itself [5,6], the target of COVID-19 vaccines, raising the possibility that vaccine effectiveness against the new variant might be seriously compromised. Additionally, although very rare previously, with the emergence of the Omicron variant, a surprisingly large proportion of previously infected individuals experienced reinfections [7,8], and breakthrough infections in vaccinated individuals were also very common [9,10], including among those in our own practice who had received a vaccine booster. These observations raised questions about the utility of boosting those with pre-existing natural or vaccine-induced immunity, with a vaccine not specifically designed for the new variant.…”

Effects of wearing FFP2 masks on SARS-CoV-2 infection rates in classrooms

“…In response, stringent mitigation measures were relaxed worldwide. 39,40 Our data show that this (at least in school settings) apparently led to "catch-up" infections in those thus far protected from infection with SARS- . By the end of our data collection (April 2022), only a small difference in cumulative infection rates was observed between students with strict mask wearing rules during the highincidence period and those without.…”