COVID-19 Vaccine May Reduce Risk of Developing Long COVID

A new study published in the journal Vaccine, shows that receiving a COVID-19 vaccine could reduce the risk of developing long COVID if it’s administered five months before an infection. The findings could help with the formulation of future vaccination strategies as COVID-19 becomes endemic.

The study, conducted by a team of investigators from Kyushu University and St. Mary’s Research Center in Japan, examined the long-term effects of COVID-19 vaccination on the incidence and risk of post-COVID-19 conditions. Data for the study was collected from the Vaccine Effectiveness, Networking and Universal Safety (VENUS) Study, an ongoing longitudinal multi-region database project that supports research on vaccine safety and effectiveness in Japan.

The study included 84,464 individuals who were diagnosed with COVID-19 between August 2020 and December 2022. Of those, 27,673 were assigned to a distant vaccine group, 25,001 to an intermediate vaccine group and 31,790 to the recently vaccinated group. The distant vaccination group developed COVID-19 365 days or more after their last vaccine dose, the intermediate group developed COVID-19 150 to 364 days after their last vaccine dose and the recent group developed COVID-19 14 to 149 days after their last vaccine dose.

The study found 11.4 percent of participants developed symptoms associated with long COVID. The group that recently received their COVID-19 vaccine had the highest prevalence of comorbidities during the year before they were vaccinated, but they had the lowest incidence of numerous conditions associated with long COVID. The distant vaccine group had the highest incidence of conditions, including acute upper respiratory disease, acute lower respiratory disease, asthma, dermatitis, ear disease, taste disorder, fatigue and headache.

Study limitations include that the analyses were conducted using claims data, that all medical conditions were identified using recorded diagnoses from the outpatient and inpatient claims data, that the type, dose and boosters of COVID-19 vaccines in each individual were not considered, that multiple comparisons were not adjusted for, and that COVID-19 reinfections or disease severity were not considered.

“There is currently insufficient information on the effects of regular booster vaccinations on post-COVID-19 conditions, but our study indicates that the risks of developing these conditions are significantly reduced when vaccinated within five months before COVID-19 occurrence,” the authors concluded. “In particular, this effect was more pronounced in older persons. The results of this study may serve as a foundation for formulating future vaccination strategies as COVID-19 transitions from a pandemic to an endemic state.”