Dataset Information

Effect of COVID-19 Vaccination on Household Transmission of SARS-CoV-2 in the Omicron Era: The Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study.

ABSTRACT:

Objective

To evaluate the effectiveness of vaccination on reducing household transmission of SARS-CoV-2 among common household types in Japan during the Omicron variant wave.

Methods

This retrospective study was conducted using vaccination records, COVID-19 infection data, and resident registry data from two Japanese municipalities. Households that experienced their first COVID-19 case between January and April 2022 were categorized into two groups according to the presence/absence of children aged ≤11 years. We constructed multivariable logistic regression models with generalized estimating equations to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for household transmission according to the vaccination statuses of primary cases and household contacts.

Results

We analyzed 7,326 households with 17,586 contacts. In all households, the OR for household transmission was <0.6 (P<0.001) when the primary case and/or contact were vaccinated. In households with children aged ≤11 years, the OR was 0.71 (P<0.001) when only the contact was vaccinated. In households with all members aged ≥12 years, the OR was <0.5 (P<0.001) when the primary case and/or contact were vaccinated.

Conclusions

COVID-19 vaccination effectively reduced household transmission in Japan during the Omicron variant wave.

SUBMITTER: Maeda M

PROVIDER: S-EPMC10289267 | biostudies-literature | 2023 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Effect of COVID-19 vaccination on household transmission of SARS-CoV-2 in the Omicron era: The Vaccine Effectiveness, Networking, and Universal Safety (VENUS) study.

Maeda Megumi M Murata Fumiko F Fukuda Haruhisa H

International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases 20230623

<h4>Objectives</h4>To evaluate the effectiveness of vaccination on reducing household transmission of SARS-CoV-2 among common household types in Japan during the Omicron variant wave.<h4>Methods</h4>This retrospective study was conducted using vaccination records, COVID-19 infection data, and resident registry data from two Japanese municipalities. Households that experienced their first COVID-19 case between January and April 2022 were categorized into two groups according to the presence/absen ...[more]

PMID: 37356650

Similar Datasets

Project description:ImportanceIn 2022, Omicron variants circulated globally, and Urumqi, China, experienced a COVID-19 outbreak seeded by Omicron BA.5 variants, resulting in the highest number of infections in the city's record before the exit of the zero COVID-19 strategy. Little was known about the characteristics of Omicron variants in mainland China.ObjectiveTo evaluate transmission characteristics of Omicron BA.5 variants and the effectiveness of inactivated vaccine (mainly BBIBP-CorV) against their transmission.Design, setting, and participantsThis cohort study was conducted using data from an Omicron-seeded COVID-19 outbreak in Urumqi from August 7 to September 7, 2022. Participants included all individuals with confirmed SARS-CoV-2 infections and their close contacts identified between August 7 and September 7, 2022 in Urumqi.ExposuresA booster dose was compared vs 2 doses (reference level) of inactivated vaccine and risk factors were evaluated.Main outcomes and measuresDemographic characteristics, timeline records from exposure to laboratory testing outcomes, contact tracing history, and contact setting were obtained. The mean and variance of the key time-to-event intervals of transmission were estimated for individuals with known information. Transmission risks and contact patterns were assessed under different disease-control measures and in different contact settings. The effectiveness of inactivated vaccine against the transmission of Omicron BA.5 was estimated using multivariate logistic regression models.ResultsAmong 1139 individuals diagnosed with COVID-19 (630 females [55.3%]; mean [SD] age, 37.4 [19.9] years) and 51 323 close contacts who tested negative for COVID-19 (26 299 females [51.2%]; mean [SD] age, 38.4 [16.0] years), the means of generation interval, viral shedding period, and incubation period were estimated at 2.8 days (95% credible interval [CrI], 2.4-3.5 days), 6.7 days (95% CrI, 6.4-7.1 days), and 5.7 days (95% CrI, 4.8-6.6 days), respectively. Despite contact tracing, intensive control measures, and high vaccine coverage (980 individuals with infections [86.0%] received ≥2 doses of vaccine), high transmission risks were found in household settings (secondary attack rate, 14.7%; 95% CrI, 13.0%-16.5%) and younger (aged 0-15 years; secondary attack rate, 2.5%; 95% CrI, 1.9%-3.1%) and older age (aged >65 years; secondary attack rate, 2.2%; 95% CrI, 1.5%-3.0%) groups. Vaccine effectiveness against BA.5 variant transmission for the booster-dose vs 2 doses was 28.9% (95% CrI, 7.7%-45.2%) and 48.5% (95% CrI, 23.9%-61.4%) for 15-90 days after booster dose. No protective outcome was detected beyond 90 days after the booster dose.Conclusions and relevanceThis cohort study revealed key transmission characteristics of SARS-CoV-2 as they evolved, as well as vaccine effectiveness against variants. These findings suggest the importance of continuously evaluating vaccine effectiveness against emerging SARS-CoV-2 variants.

Project description:We conducted a retrospective cohort study to evaluate the transmission risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2 variant and the effectiveness of inactivated COVID-19 vaccine boosters in Shenzhen during a BA.2 outbreak period from 1 February to 21 April 2022. A total of 1,248 individuals were infected with the BA.2 variant, and 7,855 close contacts were carefully investigated. The risk factors for the high secondary attack rate of SARS-CoV-2 infection were household contacts [adjusted odds ratio (aOR): 1.748; 95% confidence interval (CI): 1.448, 2.110], younger individuals aged 0-17 years (aOR: 2.730; 95% CI: 2.118, 3.518), older persons aged ≥60 years (aOR: 1.342; 95% CI: 1.135, 1.588), women (aOR: 1.442; 95% CI: 1.210, 1.718), and the subjects exposed to the post-onset index cases (aOR: 8.546; 95% CI: 6.610, 11.050), respectively. Compared with the unvaccinated and partially vaccinated individuals, a relatively low risk of secondary attack was found for the individuals who received booster vaccination (aOR: 0.871; 95% CI: 0.761, 0.997). Moreover, a high transmission risk was found for the index cases aged ≥60 years (aOR: 1.359; 95% CI: 1.132, 1.632), whereas a relatively low transmission risk was observed for the index cases who received full vaccination (aOR: 0.642; 95% CI: 0.490, 0.841) and booster vaccination (aOR: 0.676; 95% CI: 0.594, 0.770). Compared with full vaccination, booster vaccination of inactivated COVID-19 vaccine showed an effectiveness of 24.0% (95% CI: 7.0%, 37.9%) against BA.2 transmission for the adults ≥18 years and 93.7% (95% CI: 72.4%, 98.6%) for the adults ≥60 years, whereas the effectiveness was 51.0% (95% CI: 21.9%, 69.3%) for the individuals of 14 days to 179 days after booster vaccination and 51.2% (95% CI: 37.5%, 61.9%) for the non-household contacts. The estimated mean values of the generation interval, serial interval, incubation period, latent period, and viral shedding period were 2.7 days, 3.2 days, 2.4 days, 2.1 days, and 17.9 days, respectively. In summary, our results confirmed that the main transmission route of Omicron BA.2 subvariant was household contact, and booster vaccination of the inactivated vaccines was relatively effective against BA.2 subvariant transmission in older people.