Assessment of Anti-SARS-CoV-2 antibody levels among university students vaccinated with different COVID-19 primary and booster doses - fall 2021, Wisconsin.

BACKGROUND: University students commonly received COVID-19 vaccinations before returning to U.S. campuses in the Fall of 2021. Given likely immunologic variation among students based on differences in type of primary series and/or booster dose vaccine received, we conducted serologic investigations in September and December 2021 on a large university campus in Wisconsin to assess anti-SARS-CoV-2 antibody levels. METHODS: We collected blood samples, demographic information, and COVID-19 illness and vaccination history from a convenience sample of students. Sera were analyzed for both anti-spike (anti-S) and anti-nucleocapsid (anti-N) antibody levels using World Health Organization standardized binding antibody units per milliliter (BAU/mL). Levels were compared across categorical primary COVID-19 vaccine series received and binary COVID-19 mRNA booster status. The association between anti-S levels and time since most recent vaccination dose was estimated by mixed-effects linear regression. RESULTS: In total, 356 students participated, of whom 219 (61.5%) had received a primary vaccine series of Pfizer-BioNTech or Moderna mRNA vaccines and 85 (23.9%) had received vaccines from Sinovac or Sinopharm. Median anti-S levels were significantly higher for mRNA primary vaccine series recipients (2.90 and 2.86 log [BAU/mL], respectively), compared with those who received Sinopharm or Sinovac vaccines (1.63 and 1.95 log [BAU/mL], respectively). Sinopharm and Sinovac vaccine recipients were associated with a significantly faster anti-S decline over time, compared with mRNA vaccine recipients (P <.001). By December, 48/172 (27.9%) participants reported receiving an mRNA COVID-19 vaccine booster, which reduced the anti-S antibody discrepancies between primary series vaccine types. CONCLUSIONS: Our work supports the benefit of heterologous boosting against COVID-19. COVID-19 mRNA vaccine booster doses were associated with increases in anti-SARS-CoV-2 antibody levels; following an mRNA booster dose, students with both mRNA and non-mRNA primary series receipt were associated with comparable levels of anti-S IgG.

SARS-CoV-2 B.1.1.529 (Omicron) Variant Transmission Within Households - Four U.S. Jurisdictions, November 2021-February 2022.

The B.1.1.529 (Omicron) variant, first detected in November 2021, was responsible for a surge in U.S. infections with SARS-CoV-2, the virus that causes COVID-19, during December 2021-January 2022 (1). To investigate the effectiveness of prevention strategies in household settings, CDC partnered with four U.S. jurisdictions to describe Omicron household transmission during November 2021-February 2022. Persons with sequence-confirmed Omicron infection and their household contacts were interviewed. Omicron transmission occurred in 124 (67.8%) of 183 households. Among 431 household contacts, 227 were classified as having a case of COVID-19 (attack rate [AR] = 52.7%).† The ARs among household contacts of index patients who had received a COVID-19 booster dose, of fully vaccinated index patients who completed their COVID-19 primary series within the previous 5 months, and of unvaccinated index patients were 42.7% (47 of 110), 43.6% (17 of 39), and 63.9% (69 of 108), respectively. The AR was lower among household contacts of index patients who isolated (41.2%, 99 of 240) compared with those of index patients who did not isolate (67.5%, 112 of 166) (p-value <0.01). Similarly, the AR was lower among household contacts of index patients who ever wore a mask at home during their potentially infectious period (39.5%, 88 of 223) compared with those of index patients who never wore a mask at home (68.9%, 124 of 180) (p-value <0.01). Multicomponent COVID-19 prevention strategies, including up-to-date vaccination, isolation of infected persons, and mask use at home, are critical to reducing Omicron transmission in household settings.

Severe Acute Respiratory Syndrome Coronavirus 2 Transmission in a Georgia School District-United States, December 2020-January 2021.

BACKGROUND: To inform prevention strategies, we assessed the extent of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission and settings in which transmission occurred in a Georgia public school district. METHODS: During 1 December 2020-22 January 2021, SARS-CoV-2-infected index cases and their close contacts in schools were identified by school and public health officials. For in-school contacts, we assessed symptoms and offered SARS-CoV-2 reverse-transcription polymerase chain reaction (RT-PCR) testing; performed epidemiologic investigations and whole-genome sequencing to identify in-school transmission; and calculated secondary attack rate (SAR) by school setting (eg, sports, elementary school classroom), index case role (ie, staff, student), and index case symptomatic status. RESULTS: We identified 86 index cases and 1119 contacts, 688 (61.5%) of whom received testing. Fifty-nine of 679 (8.7%) contacts tested positive; 15 of 86 (17.4%) index cases resulted in ≥2 positive contacts. Among 55 persons testing positive with available symptom data, 31 (56.4%) were asymptomatic. Highest SARs were in indoor, high-contact sports settings (23.8% [95% confidence interval {CI}, 12.7%-33.3%]), staff meetings/lunches (18.2% [95% CI, 4.5%-31.8%]), and elementary school classrooms (9.5% [95% CI, 6.5%-12.5%]). The SAR was higher for staff (13.1% [95% CI, 9.0%-17.2%]) vs student index cases (5.8% [95% CI, 3.6%-8.0%]) and for symptomatic (10.9% [95% CI, 8.1%-13.9%]) vs asymptomatic index cases (3.0% [95% CI, 1.0%-5.5%]). CONCLUSIONS: Indoor sports may pose a risk to the safe operation of in-person learning. Preventing infection in staff members, through measures that include coronavirus disease 2019 vaccination, is critical to reducing in-school transmission. Because many positive contacts were asymptomatic, contact tracing should be paired with testing, regardless of symptoms.

Severe Acute Respiratory Syndrome Coronavirus 2 Testing Trends Among Persons Aged <18 Years in an Outpatient Pediatric Practice - Metropolitan Atlanta, Georgia, May-December 2020.

PURPOSE: The purpose of this study was to analyze trends in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing and test positivity among persons aged <18 years in a three-site outpatient pediatric practice in Atlanta, Georgia, serving approximately 35,000 pediatric patients. METHODS: Using electronic medical records, weekly trends in SARS-CoV-2 tests performed and the 14-day moving average of test positivity were examined, overall and by age group, during May 24-December 5, 2020. RESULTS: Among 4,995 patients who received at least 1 SARS-CoV-2 test, 6,813 total tests were completed. Overall test positivity was 5.4% and was higher among older pediatric patients (<5 years: 3.3%; 5-11 years: 4.1%; 12-17 years: 8.6%). The number of tests and test positivity increased after holidays and school breaks. CONCLUSIONS: Families might benefit from communication focused on reducing SARS-CoV-2 transmission during holidays. In addition, given higher test positivity in children aged 12-17 years, tailoring public health messaging to older adolescents could help limit SARS-CoV-2 transmission risk in this population.