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.

Evaluating a Cluster and the Overall Trend of Invasive Haemophilus influenzae Serotype b in Alaska 2005-2019.

BACKGROUND: In 2019, 5 cases of invasive Haemophilus influenzae serotype b (Hib) occurred in the Anchorage region of Alaska over a period of 16 days. No cases had occurred in Alaska in the preceding 26 months. METHODS: Alaska Hib isolates from 2005 through 2019 were analyzed using whole-genome sequencing (WGS). Rates were compared with the CDC's Active Bacterial Core surveillance (ABCs) data. RESULTS: A total of 33 cases of invasive Hib occurred in Alaska from 2005 through 2019. Of the 5 cases associated with the cluster, 2 (40%) occurred in adults and all occurred in the Anchorage region. In contrast, only 14% (4/28) of the noncluster cases occurred in this region (P < 0.01). Two cluster cases were linked epidemiologically and the bacteria were nearly identical. The other 3 cluster cases were caused by 3 genetically distinct bacteria. When the full period was evaluated, the unadjusted rate of invasive Hib disease in Alaska was 15.5 times higher in Alaska Native (AN) people than non-AN people [1.3/100,000 vs. 0.07/100,000, 95% confidence intervals (CI): 10.2-22.5). The age-adjusted rate of invasive Hib disease in Alaska was 9.4 times higher than the ABCs rate (95% CI: 6.3-14.1). CONCLUSIONS: While clustered in time and space, the 5 cases in 2019 were not due to a single bacterial strain. AN people continue to have elevated rates of invasive Hib infection compared with both non-AN people in Alaska and the ABCs population.

Vaccination Status of Alaska Native Persons With Hepatitis A Virus Infection-Alaska, 1996-2018.

Following increases in reported cases of hepatitis A, we assessed the impact of hepatitis A vaccine in Alaska Native persons. During 1996-2018, only 6 cases of hepatitis A were identified, all in unvaccinated adults. Populations can be protected against hepatitis A by achieving sufficient vaccination coverage over time.

Epidemiology of Invasive Haemophilus influenzae Serotype a Disease-United States, 2008-2017.

BACKGROUND: Haemophilus influenzae serotype a (Hia) can cause invasive disease similar to serotype b; no Hia vaccine is available. We describe the epidemiology of invasive Hia disease in the United States overall and specifically in Alaska during 2008-2017. METHODS: Active population- and laboratory-based surveillance for invasive Hia disease was conducted through Active Bacterial Core surveillance sites and from Alaska statewide invasive bacterial disease surveillance. Sterile-site isolates were serotyped via slide agglutination or real-time polymerase chain reaction. Incidences in cases per 100 000 were calculated. RESULTS: From 2008 to 2017, an estimated average of 306 invasive Hia disease cases occurred annually in the United States (estimated annual incidence: 0.10); incidence increased by an average of 11.1% annually. Overall, 42.7% of cases were in children aged <5 years (incidence: 0.64), with highest incidence among children aged <1 year (1.60). Case fatality was 7.8% overall and was highest among adults aged ≥65 years (15.1%). Among children aged <5 years, the incidence was 17 times higher among American Indian and Alaska Native (AI/AN) children (8.29) than among children of all other races combined (0.49). In Alaska, incidences among all ages (0.68) and among children aged <1 year (24.73) were nearly 6 and 14 times higher, respectively, than corresponding US incidences. Case fatality in Alaska was 10.2%, and the vast majority (93.9%) of cases occurred among AI/AN. CONCLUSIONS: Incidence of invasive Hia disease has increased since 2008, with the highest burden among AI/AN children. These data can inform prevention strategies, including Hia vaccine development.

Rural immersion as an instructional method in northern community health.

In 2004, a class of six students traveled with three faculty mentors to seven Alaska communities as part of a course designed to ground young researchers' aspirations in the pragmatics of collaborative, community-based research. This paper, authored by the students involved, discusses the process from start to finish. Beginning researchers in rural health are often daunted not by a lack of ability or ideas, but by basic issues of logistics, trust and respect. Unfortunately, they tend to remain unacquainted with these considerations until something goes wrong, and come to frame the research process as a succession of hindrances to be overcome rather than a fluid and collaborative endeavor. By placing students in working relationships with rural residents and Native elders at an early stage, the project aims to minimize common missteps and shorten the learning curve. It is hoped that our experiences can point the way toward similar efforts.