Absence of association between 2019–20 influenza vaccination and
COVID-19: results of the European I-MOVE-COVID-19 primary care project,
March–August 2020
Abstract
Background Claims of influenza vaccination increasing COVID-19 risk are
circulating. Within the I-MOVE-COVID-19 primary care multicentre study,
we measured the association between 2019–20 influenza vaccination and
COVID-19. Methods We conducted a multicentre test-negative case-control
study at primary care level, in study sites in five European countries,
from March–August 2020. Patients presenting with acute respiratory
infection were swabbed, with demographic, 2019–20 influenza vaccination
and clinical information documented. Using logistic regression we
measured the adjusted odds ratio (aOR), adjusting for study site and
age, sex, calendar time, presence of chronic conditions. The main
analysis included patients swabbed ≤7 days after onset from the three
countries with <15% of missing influenza vaccination. In
secondary analyses, we included five countries, using multiple
imputation with chained equations to account for missing data. Results
We included 257 COVID-19 cases and 1631 controls in the main analysis
(three countries). The overall aOR between influenza vaccination and
COVID-19 was 0.93 (95% CI: 0.66–1.32). The aOR was 0.92 (95% CI:
0.58–1.46) and 0.92 (95%CI: 0.51–1.67) among those aged 20–59 and
≥60 years, respectively. In secondary analyses, we included 6457 cases
and 69272 controls. The imputed aOR was 0.87 (95% CI: 0.79–0.95) among
all ages and any delay between swab and symptom onset. Conclusions There
was no evidence that COVID-19 cases were more likely to be vaccinated
against influenza than controls. Influenza vaccination should be
encouraged among target groups for vaccination. I-MOVE-COVID-19 will
continue documenting influenza vaccination status in 2020-21, in order
to learn about effects of recent influenza vaccination.