Booster Doses of COVID-19 Vaccine Are Linked to Lower Incidence of Symptoms

Health care personnel who received an additional original monovalent COVID-19 vaccine dose vs those who did not had a lower prevalence of symptoms at 6 weeks, according to study results published in Open Forum Infectious Diseases.

Researchers conducted a sub-analysis of a case-control study in the multicenter Preventing Infections through Vaccine Effectiveness Testing Project (Project PREVENT), which included health care personnel with COVID-19-like illness who tested positive and negative for SARS-CoV-2 between December 2021 and April 2022, to determine whether subsequent doses after the initial 2-dose series of the COVID-19 vaccine were associated with a lower incidence of COVID-19-like symptoms at 6 weeks postinfection. Participants were stratified into those with a positive antigen or polymerase chain reaction (PCR) test result for SARS-CoV-2 and those with a negative SARS-CoV-2 test result by PCR. Symptoms at 6 weeks were classified as general, respiratory, cardiac, neurologic, gastrointestinal, psychiatric, or other symptoms. The primary outcome was the prevalence of any symptoms of at least moderate severity at 6 weeks after illness onset. A multivariable logistic regression model was used to determine the odds of reporting symptoms at 6 weeks.

A total of 2478 health care personnel were included in the study. Baseline and 6-week surveys were completed at a median of 3 and 6 weeks after symptom onset, respectively. Most participants (77.6%) worked in acute care hospitals and 45.8% of participants were physicians or nurses.

Among the 1422 (57.4%) health care personnel who had laboratory-confirmed COVID-19, the most frequently reported symptoms were fatigue (68.4%), congestion (67.9%), and headache (65.4%). No participants were hospitalized for acute COVID-19 and no participants died.

A subsequent COVID-19 vaccine dose was received by 1643 (66.3%) participants. Uptake of an additional vaccine dose was greater among those who were COVID-19-negative (79.5%) than those who were COVID-19-positive (56.5%; difference, 25.3%; 95% CI, 21.3%-29.2%).

Among those with COVID-19, 373 (26.2%) participants reported symptoms at 6 weeks. At least 1 neurologic, respiratory, and cardiac symptom was reported by 156 (11.0%), 120 (8.4%), and 19 (1.3%) participants, respectively. Among those who tested negative for SARS-CoV-2, 195 (18.5%) participants reported symptoms at 6 weeks. At least 1 neurologic, respiratory, and cardiac symptom was reported by 73 (6.9%), 47 (4.5%), and 6 (0.6%) participants, respectively. Fatigue (11.2%) and sleep difficulty (6.5%) after 6 weeks were most strongly associated with having had COVID-19.

Participants with COVID-19 who received an additional COVID-19 vaccine dose vs those who did not had a lower prevalence of any symptoms (adjusted odds ratio [aOR], 0.55; 95% CI, 0.43-0.70) at 6 weeks. The strongest association between receipt of an additional vaccine dose and specific symptoms was for cardiac complaints (aOR, 0.25; 95% CI, 0.07-0.66).

Among participants who were negative for SARS-CoV-2, no statistical association was found between receipt of an additional vaccine dose and 6-week symptoms (aOR, 0.87; 95% CI, 0.59-1.29).

Study limitations include potential misclassification and recall bias, inability to assess all vaccine formulations, small sample size, and reduced generalizability of results to HCPs who were hospitalized.

“Our findings add to evidence of the benefit of COVID-19 vaccines, not only in preventing infection and severe illness, but also in improving recovery from COVID-19,” the study authors concluded.

This article originally appeared on Infectious Disease Advisor