COVID-19

Objective: To evaluate the personal protective effects of wearing versus not wearing surgical face masks in public spaces on self-reported respiratory symptoms over a 14 day period.

Design: Pragmatic randomised superiority trial.

Setting: Norway.

Participants: 4647 adults aged ≥18 years: 2371 were assigned to the intervention arm and 2276 to the control arm.

Interventions: Participants in the intervention arm were assigned to wear a surgical face mask in public spaces (eg, shopping centres, streets, public transport) over a 14 day period (mask wearing at home or work was not mentioned). Participants in the control arm were assigned to not wear a surgical face mask in public places.

Main outcome measures: The primary outcome was self-reported respiratory symptoms consistent with a respiratory infection. Secondary outcomes included self-reported and registered covid-19 infection.

Results: Between 10 February 2023 and 27 April 2023, 4647 participants were randomised of whom 4575 (2788 women (60.9%); mean age 51.0 (standard deviation 15.0) years) were included in the intention-to-treat analysis: 2313 (50.6%) in the intervention arm and 2262 (49.4%) in the control arm. 163 events (8.9%) of self-reported symptoms consistent with respiratory infection were reported in the intervention arm and 239 (12.2%) in the control arm. The marginal odds ratio was 0.71 (95% confidence interval (CI) 0.58 to 0.87; P=0.001) favouring the face mask intervention. The absolute risk difference was -3.2% (95% CI -5.2% to -1.3%; P<0.001). No statistically significant effect was found on self- reported (marginal odds ratio 1.07, 95% CI 0.58 to 1.98; P=0.82) or registered covid-19 infection (effect estimate and 95% CI not estimable owing to lack of events in the intervention arm).

Conclusion: Wearing a surgical face mask in public spaces over 14 days reduces the risk of self-reported symptoms consistent with a respiratory infection, compared with not wearing a surgical face mask.

Trial registration: ClinicalTrials.gov NCT05690516.

A 43-year-old woman presented with a 1-year history of recurring symptoms of sudden onset of fatigue, palpitations, dyspnea, chest pain, lightheadedness, and nausea that were associated with standing and resolved with sitting. These symptoms began 1 month after mild COVID-19 infection. At presentation, while supine, blood pressure (BP) was 123/70 mm Hg and heart rate (HR) was 90/min; while seated, BP was 120/80 and HR was 93/min; after standing for 1 minute, BP was 124/80 and HR was 119/min. Physical examination results were normal. Oxygen saturation was 98% at rest while breathing room air. She had no oxygen desaturation during a 6-minute walk test but walked only 282 m (45% predicted). Complete blood cell count, morning cortisol, and thyrotropin blood levels were normal. Electrocardiogram (ECG), chest computed tomography, pulmonary function testing, methacholine challenge, bronchoscopy, echocardiography, and cardiac catheterization findings were normal. During tilt table testing, the patient experienced lightheadedness and nausea when moved from horizontal to the upright position. Results of the tilt table test are shown in the Table and Figure.

Background
To evaluate the duration of protection against reinfection conferred by a previous SARS-CoV-2 infection in children and adolescents.
Methods
We applied two complementary approaches: a matched test-negative, case-control design and a retrospective cohort design. 458,959 unvaccinated individuals aged 5-18 years were included. Analyses focused on July 1 to December 13, 2021, a period of Delta variant dominance in Israel. We evaluated three SARS-CoV-2-related outcomes: documented PCR confirmed infection or reinfection, symptomatic infection or reinfection, and SARS-CoV-2-related hospitalization or death.
Findings
Overall, children and adolescents who were previously infected acquired durable protection against reinfection with SARS-CoV-2 for at least 18 months. Importantly, no SARS-CoV-2-related deaths were recorded in either the SARS-CoV-2 naïve group or the previously infected group. Effectiveness of naturally-acquired immunity against a recurrent infection reached 89.2% (95% CI: 84.7%-92.4%) three to six months after first infection, mildly declining to 82.5% (95% CI, 79.1%-85.3%) 9-12 months after infection, with a slight non-significant waning trend up to 18 months after infection. Additionally, we found that ages 5-11 years exhibited no significant waning of naturally acquired protection throughout the outcome period, whereas waning protection in the 12-18 year-old age group was more prominent, but still mild.
Interpretation
Children and adolescents who were previously infected with SARS-CoV-2 remain protected to a high degree for 18 months. Further research is needed to examine naturally-acquired immunity against Omicron and newer emerging variants.

The aims of this rapid systematic review are to synthesize evidence on the prevalence, levels, and durability of the antibody response to SARS-CoV-2 infection among adults and how antibodies correlate with protective immunity. Given the rapidly evolving evidence within this field, the Agency for Healthcare Research and Quality’s Evidence-based Practice Center (AHRQ EPC) Program will maintain this report as a living review with planned ongoing literature surveillance and critical appraisal. We will provide regular report updates as additional evidence becomes available, modifying the scope of the review as new directions in SARS-CoV-2 immunity research emerge. This review was conducted in coordination with the American College of Physicians (ACP) as part of AHRQ’s standing work to provide health professional organizations and systems with evidence reviews to support the development of clinical guidance for their clinician members.