TY - JOUR
T1 - The indirect effect of mRNA-based COVID-19 vaccination on healthcare workers’ unvaccinated household members
AU - Salo, Jussipekka
AU - Hägg, Milla
AU - Kortelainen, Mika
AU - Leino, Tuija
AU - Saxell, Tanja
AU - Siikanen, Markku
AU - Sääksvuori, Lauri
N1 - Funding Information:
M.K. is supported part by the InFLAMES Flagship Programme of the Academy of Finland (decision number: 33750). L.S. is supported part by the INVEST Flagship Programme of the Academy of Finland (decision number: 320161).
Publisher Copyright:
© 2022, The Author(s).
PY - 2022/3/4
Y1 - 2022/3/4
N2 - Mass vaccination is effective in reducing SARS-CoV-2 infections among vaccinated individuals. However, it remains unclear how effectively COVID-19 vaccines prevent people from spreading the virus to their close contacts. Using nationwide administrative datasets on SARS-CoV-2 infections, vaccination records, demographics, and unique household IDs, we conducted an observational cohort study to estimate the direct and indirect effectiveness of mRNA-based COVID-19 vaccines in reducing infections among vaccinated healthcare workers and their unvaccinated household members. Our estimates for adults imply indirect effectiveness of 39.1% (95% CI: −7.1% to 65.3%) two weeks and 39.0% (95% CI: 18.9% to 54.0%) eight weeks after the second dose. We find that the indirect effect of mRNA-based COVID-19 vaccines within households is smaller for unvaccinated children than for adults and statistically insignificant. Here, we show that mRNA-based COVID-19 vaccines are associated with a reduction in SARS-CoV-2 infections not only among vaccinated individuals but also among unvaccinated adult household members in a real-world setting.
AB - Mass vaccination is effective in reducing SARS-CoV-2 infections among vaccinated individuals. However, it remains unclear how effectively COVID-19 vaccines prevent people from spreading the virus to their close contacts. Using nationwide administrative datasets on SARS-CoV-2 infections, vaccination records, demographics, and unique household IDs, we conducted an observational cohort study to estimate the direct and indirect effectiveness of mRNA-based COVID-19 vaccines in reducing infections among vaccinated healthcare workers and their unvaccinated household members. Our estimates for adults imply indirect effectiveness of 39.1% (95% CI: −7.1% to 65.3%) two weeks and 39.0% (95% CI: 18.9% to 54.0%) eight weeks after the second dose. We find that the indirect effect of mRNA-based COVID-19 vaccines within households is smaller for unvaccinated children than for adults and statistically insignificant. Here, we show that mRNA-based COVID-19 vaccines are associated with a reduction in SARS-CoV-2 infections not only among vaccinated individuals but also among unvaccinated adult household members in a real-world setting.
UR - http://www.scopus.com/inward/record.url?scp=85125869509&partnerID=8YFLogxK
U2 - 10.1038/s41467-022-28825-4
DO - 10.1038/s41467-022-28825-4
M3 - Article
C2 - 35246536
AN - SCOPUS:85125869509
SN - 2041-1723
VL - 13
SP - 1
EP - 7
JO - Nature Communications
JF - Nature Communications
IS - 1
M1 - 1162
ER -
