Flu vaccine linked to better COVID-19 symptoms
People who received the flu vaccine prior to having COVID-19 had less risk of sepsis, stroke, deep vein thrombosis (DVT), and disease requiring emergency or intensive care, according to a study presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) this year.
The researchers looked at 74,754 patients in the international TriNetX research database: All had been diagnosed as having COVID-19, but half had received flu shots 2 weeks to 6 months prior to the infection. Patients were matched across COVID risk factors (eg, age, ethnicity, health conditions) and followed up at 30, 60, 90, and 120 days post-diagnosis.
The group that did receive the flu shot had significantly lower risk for sepsis (risk ratio [RR], 1.36 to 1.45; 95% confidence interval [CI], 1.12 to 1.70) and stroke (RR, 1.45 to 1.58; 95% CI, 1.08 to 2.03) across all time points. While intensive care unit (ICU) admissions did not show a significant association for 60 days, for the other time points, it was tied to a risk ratio of 1.17 to 1.20 (95% CI, 1.00 to 1.39).
Patients who received the flu vaccine also had significantly fewer DVTs 60 to 120 days post-diagnosis (RR, 1.41 to 1.53; 95% CI, 1.08 to 2.08) and, from days 90 to 120 post-diagnosis, significantly fewer emergency department visits (RR, 1.20 to 1.58; 95% CI, 1.05 to 1.48).
Flu vaccine was not linked with reduced risk of death.
"Only a small fraction of the world has been fully vaccinated against COVID-19 to date and, with all the devastation that has occurred due to the pandemic, the global community still needs to find solutions to reduce morbidity and mortality," said senior author Devinder Singh, MD, in a European Society of Clinical Microbiology and Infectious Disease (ESCMID) press release. This does not mean, however, that the flu vaccine can act as a replacement for COVID-19 vaccination, the researchers add.
Jul 11 ECCMID abstract
Jul 11 ESCMID press release
Single dose of COVID vaccines provides good protection in elderly
A single dose of an mRNA-based COVID-19 vaccine reduced SARS-CoV-2 infection risk by about two-thirds in the elderly, according to a Clinical Infectious Diseases study late last week.
The researchers looked at 16,993 sample specimens from British Columbia residents 70 years or older during the area's spring wave (Apr 4 to May 1). Of the samples, 7.2% tested positive, of which 92% (1,131) were genetically characterized and consisted of 45% Alpha (B117), 14% Gamma (P1), and 14% non-variants of concern (non-VOCs). Participants were considered vaccinated if they had received their first dose of either the Pfizer/BioNTech vaccine or the Moderna vaccine at least 21 days prior to specimen collection.
Overall, vaccine effectiveness (VE) for a single mRNA dose at 21 or more days post-vaccination was 65% (95% confidence interval [CI], 58% to 71%). VE was highest against non-VOCs (72%; 95% CI, 58% to 81%), but it was still high against Alpha and Gamma (respectively, 67%; 95% CI, 57% to 75%, and 61%; 95% CI, 45% to 72%).
Prior to 21 days after vaccination, VE was lower: At days 0 to 13, VE was considered negligible at 14%, and from days 14 to 20, it was 43%. After day 21, however, the researchers note that single-dose VE increased to 75% (95% CI, 58 to 83; days 35 to 41 days).
"Substantial single-dose protection in older adults reinforces the option to defer second doses when vaccine supply is scarce and broader first-dose coverage is rapidly needed," write the researchers. "Such strategy, however, warrants further evaluation to assess duration of protection over a longer period and against additional VOC."
Jul 9 Clin Infect Dis study