Characteristics of Decedents With COVID-19-Related Mortality in Kentucky, July 1-August 13, 2021.

OBJECTIVE: Although vaccination reduces the risk of severe COVID-19, fatal COVID-19 cases after vaccination can occur. We examined the characteristics of decedents with COVID-19-related mortality to help inform discussions about vaccination, boosters, and mitigation strategies. METHODS: We examined COVID-19-related deaths in Kentucky resulting from infections occurring from July 1 through August 13, 2021. We used records from case investigations, medical records, the Kentucky Health Information Exchange, and the Kentucky Immunization Registry to determine demographic information, vaccination status, and underlying health conditions, including calculation of the Charlson Comorbidity Index (CCI). We calculated mortality incidence rates by vaccination status by using data for unvaccinated and fully vaccinated populations in Kentucky as of July 1, 2021. RESULTS: In total, 777 COVID-19-related deaths occurred in Kentucky during the study period; 592 (76.2%) occurred among unvaccinated people. Compared with unvaccinated decedents, fully vaccinated decedents were older (median age, 77 vs 65 years; P < .001), had higher comorbidity levels (median CCI, 3 vs 1; P < .001), and were more likely to have immunocompromised health status (26.4% vs 16.0%; P = .003). Diabetes, hypertension, heart disease, and chronic lung disease were more common among vaccinated decedents than among unvaccinated decedents. Unvaccinated adults had a significantly higher risk of death than fully vaccinated adults (incidence rate ratio for age 20-49 years: 20.5 [95% CI, 6.5-64.8]; 50-64 years: 14.6 [95% CI, 9.4-22.7]; ≥65 years: 10.2 [95% CI, 8.3-12.4]). CONCLUSIONS: Immunocompromised health status, older age, and higher comorbidity were prevalent among fully vaccinated decedents, suggesting adults with these characteristics may benefit from additional protection strategies. Further understanding of the protection of additional and booster doses is needed.

Evaluating risk factors associated with COVID-19 infections among vaccinated people early in the U.S. vaccination campaign: an observational study of five states, January-March 2021.

BACKGROUND: COVID-19 vaccines are an effective tool to prevent illness due to SARS-CoV-2 infection. However, infection after vaccination still occurs. We evaluated all infections identified among recipients of either the Pfizer-BioNTech or Moderna COVID-19 vaccine in five U.S. states during January-March 2021. METHODS: Using observational data reported to CDC, we compared the incidence of SARS-CoV-2 infection among vaccinated and unvaccinated persons, and the sex, age, and vaccine product received for individuals with vaccine breakthrough infections to those of the vaccinated population using Poisson regression models. We also compared the proportion of vaccine breakthrough cases due to a SARS-CoV-2 variant of concern to data reported to CDC's national genomic surveillance program. RESULTS: The age-adjusted incidence of reported SARS-CoV-2 infection was 97% lower among vaccinated as compared to unvaccinated persons aged ≥ 16 years (68 vs 2252 cases per 100,000 people). Vaccinated adults aged ≥ 85 years were 1.6 times (95% CI 1.3-1.9) as likely to become infected with SARS-CoV-2 than vaccinated adults aged < 65 years. Pfizer-BioNTech COVID-19 vaccine recipients were 1.4 times (95% CI 1.3-1.6) as likely to experience infection compared to Moderna COVID-19 recipients. The proportion of infections among vaccinated persons caused by SARS-CoV-2 variants of concern was similar to the proportion of circulating viruses identified as variants of concern in the five states during the same time. CONCLUSIONS: Vaccinated persons had a substantially lower incidence of SARS-CoV-2 infection compared to unvaccinated persons. Adults aged ≥ 85 years and Pfizer-BioNTech vaccine recipients had a higher risk of infection following vaccination. We provide an analytic framework for ongoing evaluation of patterns associated with SARS-CoV-2 infection among vaccinated persons using observational surveillance and immunization data. Our findings reinforce the effectiveness of COVID-19 vaccines in preventing infection in real-world settings.

Association of Severe Acute Respiratory Syndrome Coronavirus 2 Vaccination or a Prior Positive Test Result in Adolescents during the Delta Variant Surge in Kentucky.

In a cross-sectional study of 89 736 adolescents in Kentucky, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination provided an estimated protection against infection of 81% when the highly transmissible Delta variant was predominant. Vaccination provided added benefit to those with a history of prior infection. These findings support the recommendation that all adolescents receive SARS-CoV-2 vaccination.

Protective Immunity after Natural Infection with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) - Kentucky, USA, 2020.

BACKGROUND: As vaccine supply and access remain limited in many parts of the world, understanding the duration of protection from reinfection after natural infection is important. METHODS: Distinct individuals testing positive and negative for SARS-CoV-2 between March 6, 2020, and August 31, 2020, in Kentucky, USA, were identified using the Kentucky National Electronic Disease Surveillance System. Individuals were followed for occurrence of a positive test for SARS-CoV-2 from 91 days after their initial test result through December 31, 2020. Protection from reinfection provided by a prior infection was calculated and additional analyses evaluated impact of age, sex, symptom status, long-term care facility connection, testing occurrence and frequency, and time from initial infection. RESULTS: The protective effect from prior infection was 80.3% (95% CI, 78.2%-82.2%) for those aged 20-59 years and 67.4% (95% CI, 62.8%-71.4%) for those aged ≥60 years. At 30-day time periods through 270 days (with limited exceptions), protection was estimated to be >75% for those aged 20-59 years and >65% for those aged ≥60 years. Factors associated with repeat positive testing included a connection to a long-term care facility, duration of potential exposure, and absence of symptoms during initial infection. CONCLUSIONS: Natural infection provides substantial and persistent immunologic protection for a period of several months for most individuals, although subpopulations may be at greater risk of repeat positive testing and potential poor outcomes associated with reinfection. These subgroups include individuals aged ≥60 years, residents and staff of long-term care facilities, and those who have mild or asymptomatic illness with initial infection. Continued emphasis on vaccination and infection prevention and control strategies remains critically important in reducing the risk of reinfection and associated severe outcomes for these groups.

Reduced Risk of Reinfection with SARS-CoV-2 After COVID-19 Vaccination - Kentucky, May-June 2021.

Although laboratory evidence suggests that antibody responses following COVID-19 vaccination provide better neutralization of some circulating variants than does natural infection (1,2), few real-world epidemiologic studies exist to support the benefit of vaccination for previously infected persons. This report details the findings of a case-control evaluation of the association between vaccination and SARS-CoV-2 reinfection in Kentucky during May-June 2021 among persons previously infected with SARS-CoV-2 in 2020. Kentucky residents who were not vaccinated had 2.34 times the odds of reinfection compared with those who were fully vaccinated (odds ratio [OR] = 2.34; 95% confidence interval [CI] = 1.58-3.47). These findings suggest that among persons with previous SARS-CoV-2 infection, full vaccination provides additional protection against reinfection. To reduce their risk of infection, all eligible persons should be offered vaccination, even if they have been previously infected with SARS-CoV-2.

COVID-19 Outbreak Associated with a SARS-CoV-2 R.1 Lineage Variant in a Skilled Nursing Facility After Vaccination Program - Kentucky, March 2021.

Although COVID-19 mRNA vaccines demonstrated high efficacy in clinical trials (1), they were not 100% efficacious. Thus, some infections postvaccination are expected. Limited data are available on effectiveness in skilled nursing facilities (SNFs) and against emerging variants. The Kentucky Department for Public Health (KDPH) and a local health department investigated a COVID-19 outbreak in a SNF that occurred after all residents and health care personnel (HCP) had been offered vaccination. Among 83 residents and 116 HCP, 75 (90.4%) and 61 (52.6%), respectively, received 2 vaccine doses. Twenty-six residents and 20 HCP received positive test results for SARS-CoV-2, the virus that causes COVID-19, including 18 residents and four HCP who had received their second vaccine dose >14 days before the outbreak began. An R.1 lineage variant was detected with whole genome sequencing (WGS). Although the R.1 variant has multiple spike protein mutations, vaccinated residents and HCP were 87% less likely to have symptomatic COVID-19 compared with those who were unvaccinated. Vaccination of SNF populations, including HCP, is critical to reduce the risk for SARS-CoV-2 introduction, transmission, and severe outcomes in SNFs. An ongoing focus on infection prevention and control practices is also essential.

Suspected Recurrent SARS-CoV-2 Infections Among Residents of a Skilled Nursing Facility During a Second COVID-19 Outbreak - Kentucky, July-November 2020.

Reinfection with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), is believed to be rare (1). Some level of immunity after SARS-CoV-2 infection is expected; however, the evidence regarding duration and level of protection is still emerging (2). The Kentucky Department for Public Health (KDPH) and a local health department conducted an investigation at a skilled nursing facility (SNF) that experienced a second COVID-19 outbreak in October 2020, 3 months after a first outbreak in July. Five residents received positive SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) test results during both outbreaks. During the first outbreak, three of the five patients were asymptomatic and two had mild symptoms that resolved before the second outbreak. Disease severity in the five residents during the second outbreak was worse than that during the first outbreak and included one death. Because test samples were not retained, phylogenetic strain comparison was not possible. However, interim period symptom resolution in the two symptomatic patients, at least four consecutive negative RT-PCR tests for all five patients before receiving a positive test result during the second outbreak, and the 3-month interval between the first and the second outbreaks, suggest the possibility that reinfection occurred. Maintaining physical distance, wearing face coverings or masks, and frequent hand hygiene are critical mitigation strategies necessary to prevent transmission of SARS-CoV-2 to SNF residents, a particularly vulnerable population at risk for poor COVID-19-associated outcomes.* Testing, containment strategies (isolation and quarantine), and vaccination of residents and health care personnel (HCP) are also essential components to protecting vulnerable residents. The findings of this study highlight the importance of maintaining public health mitigation and protection strategies that reduce transmission risk, even among persons with a history of COVID-19 infection.