The prevalence of SARS-CoV-2 infection and other public health outcomes during the BA.2/BA.2.12.1 surge, New York City, April–May 2022

Abstract

Background Routine case surveillance data for SARS-CoV-2 are incomplete, unrepresentative, missing key variables of interest, and may be increasingly unreliable for timely surge detection and understanding the true burden of infection. Methods We conducted a cross-sectional survey of a representative sample of 1030 New York City (NYC) adult residents ≥18 years on May 7-8, 2022. We estimated the prevalence of SARS-CoV-2 infection during the preceding 14-day period. Respondents were asked about SARS-CoV-2 testing, testing outcomes, COVID-like symptoms, and contact with SARS-CoV-2 cases. SARS-CoV-2 prevalence estimates were age- and sex-adjusted to the 2020 U.S. population. We triangulated survey-based prevalence estimates with contemporaneous official SARS-CoV-2 counts of cases, hospitalizations, and deaths, as well as SARS-CoV-2 wastewater concentrations. Results We show that 22.1% (95% CI 17.9–26.2%) of respondents had SARS-CoV-2 infection during the two-week study period, corresponding to ~1.5 million adults (95% CI 1.3-1.8 million). The official SARS-CoV-2 case count during the study period is 51,218. Prevalence is estimated at 36.6% (95% CI 28.3–45.8%) among individuals with co-morbidities, 13.7% (95% CI 10.4–17.9%) among those 65+ years, and 15.3% (95% CI 9.6–23.5%) among unvaccinated persons. Among individuals with a SARS-CoV-2 infection, hybrid immunity (history of both vaccination and infection) is 66.2% (95% CI 55.7–76.7%), 44.1% (95% CI 33.0–55.1%) were aware of the antiviral nirmatrelvir/ritonavir, and 15.1% (95% CI 7.1–23.1%) reported receiving it. Hospitalizations, deaths and SARS-CoV-2 virus concentrations in wastewater remained well below that during the BA.1 surge. Conclusions Our findings suggest that the true magnitude of NYC’s BA.2/BA.2.12.1 surge may have been vastly underestimated by routine case counts and wastewater surveillance. Hybrid immunity, bolstered by the recent BA.1 surge, likely limited the severity of the BA.2/BA.2.12.1 surge.

“Boosting” Surveillance for a More Impactful Public Health Response During Protracted and Evolving Infectious Disease Threats: Insights From the COVID-19 Pandemic

“…However, during the BA.2/BA.2.12.1 surge, we also found that 50.6% of New York City adults had hybrid protection conferred from both vaccination and prior infection, compared with 30.9% who had vaccine-induced immunity only, 11.5% with infected-induced immunity only, and 7.0% with no immunity. 8 Our findings suggest that a smaller proportion of the population may have been vulnerable to severe outcomes during the BA.2/BA.2.12.1 surge compared with the BA.1 surge.…”

“…In 2 different surveys in New York City that measured at-home testing—including probable cases and positive cases—the prevalence of SARS-CoV-2 substantially increased compared with prevalence estimates based solely on reported health and laboratory provider tests. 7 , 8 Among New York City residents who tested for SARS-CoV-2, at-home test use among adults almost doubled during a 10-week period of the BA.1 surge and a 2-week period of the BA.2 surge. These findings show that a substantial proportion of the population is using at-home tests without receiving a confirmatory test.…”

“…Using medical vulnerability to severe COVID-19 outcomes, as defined using CDC criteria, 50 we estimated that during the BA.2/BA.2.12.1 surge in New York City, 8 SARS-CoV-2 prevalence among medically vulnerable adults was 2.5 times higher than other adults. However, during the BA.2/BA.2.12.1 surge, we also found that 50.6% of New York City adults had hybrid protection conferred from both vaccination and prior infection, compared with 30.9% who had vaccine-induced immunity only, 11.5% with infected-induced immunity only, and 7.0% with no immunity.…”

“…We highlight the use of routinely and strategically deployed population-representative surveys as a possible remedy to address key surveillance gaps. We draw on insights gained from 3 strategically deployed population-based surveys in New York City and the United States during major Omicron variant surges, including BA.1, 7 BA.2, 8 and BA.4/BA.5. 9 , 10 …”

Representative Public Health Surveys Pose Several Challenges: Lessons Learned Across 9 Communities During the COVID-19 Pandemic

“… 2 Surveillance surveys with representative sampling methods have revealed much higher and more reliable estimates of COVID-19 infection. 1 , 3 Additionally, assessing samples for SARS-CoV-2–specific antibodies improves reliability of population prevalence estimates of natural infection. 1 The main objective of these surveillance surveys was to provide timely, reliable prevalence estimates to local public health officials to inform their decision-making efforts in response to the COVID-19 pandemic.…”