According to a new report released by the Centers for Disease Control and Prevention (CDC), by February 2022, nearly 60% of people in the United States will have been infected with SARS-CoV-2. Previous seroprevalence studies had shown that by December 2021, roughly one out of every three Americans had Covid-19 at least once since the pandemic began. The most recent findings highlight the Omicron variant’s extreme contagiousness and its widespread across the United States.
While official infection numbers will always be underestimated – owing to failures to test and detect mild or asymptomatic cases, or people failing to report positive results of at-home rapid tests – seroprevalence surveys, such as those conducted by the CDC, can help provide better estimates of how many people have actually contracted the virus. “We know that the reported cases are only the tip of the iceberg,” said Kristie Clarke, co-leader of the Covid-19 Epidemiology & Surveillance Taskforce Seroprevalence Team at the CDC.
Thus, from December 2021 to February 2022, seroprevalence increased dramatically among children aged 11 or younger and adolescents aged 12 to 17, rising from 44.2 to 75.2 percent and 45.6 to 74.2 percent, respectively. During the Omicron surge, seroprevalence increased from 36.5 to 63.7 percent among adults aged 18 to 49, and from 28.8 to 49.8 percent among people aged 50 to 64. Seroprevalence increased from 19.1 to 33.2 percent in seniors over the age of 65, most likely reflecting the increased precautions older people still took against Covid during that time period.
While these impressive numbers may lead many people to believe that the United States is on its way to herd immunity, the emergence of Omicron at the end of last year demonstrated that SARS-CoV-2 can mutate in ways that allow it to evade previously acquired immunity. “We do believe there is a lot of protection in the community, both from vaccination, boosting, and prior infection,” CDC Director Rochelle Walensky added. “That said, we cannot emphasize enough how important it is for those who have detectable antibodies from infection to get vaccinated.”