Presence of symptoms 6 weeks after COVID-19 among vaccinated and unvaccinated US healthcare personnel: a prospective cohort study

Abstract

Objectives: Although COVID-19 vaccines offer protection against infection and severe disease, there is limited information on the effect of vaccination on prolonged symptoms following COVID-19. Our objective was to determine differences in prevalence of prolonged symptoms 6 weeks after onset of COVID-19 among healthcare personnel (HCP) by vaccination status, and to assess differences in timing of return to work.

Design: Cohort analysis of HCP with COVID-19 enrolled in a multicentre vaccine effectiveness study. HCP with COVID-19 between December 2020 and August 2021 were followed up 6 weeks after illness onset.

Setting: Health systems in 12 US states.

Participants: HCP participating in a vaccine effectiveness study were eligible for inclusion if they had laboratory-confirmed symptomatic SARS-CoV-2 with mRNA vaccination (symptom onset ≥14 days after two doses) or no prior vaccination. Among 681 eligible participants, 419 (61%) completed a follow-up survey to assess symptoms reported 6 weeks after illness onset.

Exposures: Two doses of a COVID-19 mRNA vaccine compared with no COVID-19 vaccine.

Main outcome measures: Prevalence of symptoms 6 weeks after onset of COVID-19 illness and days to return to work.

Results: Among 419 HCP with COVID-19, 298 (71%) reported one or more COVID-like symptoms 6 weeks after illness onset, with a lower prevalence among vaccinated participants compared with unvaccinated participants (60.6% vs 79.1%; adjusted risk ratio 0.70, 95% CI 0.58 to 0.84). Following their illness, vaccinated HCP returned to work a median 2.0 days (95% CI 1.0 to 3.0) sooner than unvaccinated HCP (adjusted HR 1.37, 95% CI 1.04 to 1.79).

Conclusions: Receipt of two doses of a COVID-19 mRNA vaccine among HCP with COVID-19 illness was associated with decreased prevalence of COVID-like symptoms at 6 weeks and earlier return to work.

Keywords: COVID-19; EPIDEMIOLOGY; INFECTIOUS DISEASES.

Figure 1

Enrolment of COVID-19 vaccinated and unvaccinated US healthcare personnel.

Figure 2

Prevalence of new or persistent symptoms 6 weeks after COVID-19 symptom onset among US healthcare personnel. Each bar in the left pane shows the percentage of participants reporting symptoms at the 6-week follow-up, stratified by vaccination status. For each symptom, the relative risk (RR, unadjusted) and 95% CI are shown on the forest plot to the right. For RR <1.0, the symptom is less prevalent among the vaccinated. Note that several symptoms are part of both COVID-19 symptoms and neurological symptoms. COVID-like symptoms included fever, cough, dyspnoea, chills, fatigue, myalgia, headache, new loss of taste or smell, sore throat, nasal congestion, diarrhoea and nausea or vomiting. Neurological symptoms included dizziness, headache, muscle weakness, movement disorders, confusion, memory difficulties, concentration problems or loss of taste or smell. Any symptoms included trouble sleeping, exercise problems, chest pain or abdominal pain, in addition to COVID-19 symptoms and neurological symptoms, defined above.

Figure 3

New or persistent symptoms at 6 weeks after COVID-19 symptom onset in vaccinated versus unvaccinated US healthcare personnel. Each bar in the left pane shows the percentage of participants reporting symptoms at the 6-week follow-up, stratified by vaccination status. This forest plot in the right pane shows the estimated risk of new or persistent symptoms present at the 6-week survey. The relative risk (RR) shows the ratio between the probability of having symptoms in the vaccinated versus the unvaccinated (values <1.0 indicate that the prevalence of symptoms is lower in the vaccinated than the unvaccinated group). Grey circles show the unadjusted estimates and black squares show the estimates adjusted for age, race, ethnicity, comorbidities, calendar month of diagnosis and weeks since symptoms started. Error bars indicate 95% CIs around the point estimate. COVID-like symptoms included fever, cough, dyspnoea, chills, fatigue, myalgia, headache, new loss of taste or smell, sore throat, nasal congestion, diarrhoea and nausea or vomiting. Neurological symptoms included dizziness, headache, muscle weakness, movement disorders, confusion, memory difficulties, concentration problems or loss of taste or smell. Any symptoms included trouble sleeping, exercise problems, chest pain or abdominal pain, in addition to COVID-19 symptoms and neurological symptoms, defined above. *Adjusted for age, race, ethnicity, comorbidities, calendar month of diagnosis and weeks since symptoms started.

Figure 4

Kaplan-Meier plot of proportion of US healthcare personnel returning to work after onset of COVID-19 symptoms, stratified on COVID-19 vaccination. The Kaplan-Meier plot shows the actual time to return to work, stratified by vaccination status (log-rank test, p<0.001). A Cox proportional hazards model was constructed, adjusting for age, race, ethnicity, comorbidities and calendar month of diagnosis. The adjusted HR (aHR) for the adjusted model is 1.37 (95% CI 1.04 to 1.79). Note that aHR >1.0 indicates that participants resume work more quickly.