Advice on monoclonal antibodies; new data on long-term COVID-19 symptoms, vaccine efficacy

The NIH's COVID-19 treatment guidelines panel provided guidance on triaging monoclonal antibody therapy on Sept. 3. There aren't currently shortages of the drugs, but logistical constraints can still make it difficult to administer them to all eligible patients, the panel noted. If that is the case, the panel suggests prioritizing treatment of COVID-19 infection over postexposure prophylaxis and prioritizing unvaccinated or incompletely vaccinated patients at high risk of progressing to severe COVID-19 and vaccinated patients who are not expected to mount an adequate immune response (e.g., immunocompromised patients) over others. When there are no logistical constraints, these considerations should not limit the provision of anti-SARS-CoV-2 monoclonal antibodies, the panel added.

A Dutch study found persistent COVID-19 symptoms to be common, especially among women and obese patients. The year-long study, published by Clinical Infectious Diseases on Sept. 2, included 342 COVID-19 patients, 71% with mild or moderate disease. At 12 months, 40.7% of patients continued to report at least one symptom. Recovery was slower in female versus male patients (adjusted hazard ratio, 0.65; 95% CI, 0.47 to 0.92) and patients with a body mass index of 30 kg/m² versus less than 25 kg/m² (adjusted hazard ratio, 0.62; 95% CI, 0.39 to 0.97). The study authors recommended providing early intervention for these two populations. They also noted that their results indicated that “recovery beyond approximately 6 months after illness onset is uncommon, suggesting that individuals who remain symptomatic beyond this point may require more intensive support and care.”

Symptoms often associated with SARS-CoV-2 infection that lasted at least a month were more common among patients who tested positive for SARS-CoV-2 than those who tested negative, according to the results of a survey published in the Sept. 10 MMWR. A comparison of patients who reported any initial symptom often associated with SARS-CoV-2 infection (603 with positive tests and 1,526 with negative tests) showed that persistent (>4 weeks) symptoms were more common with positive tests than negative (76.2% vs. 69.6%; P=0.005). More than a quarter of the SARS-CoV-2-positive patients with long-term symptoms reported believing that COVID-19 vaccination made their symptoms better (versus 15.7% of those with negative tests).

Several studies provided further evidence of the safety and effectiveness of COVID-19 vaccines. An interim analysis from the Vaccine Safety Datalink, published by JAMA on Sept. 3, looked at more than 11 million doses of the mRNA vaccines given to 6.2 million patients. It found no increase in incidence of serious outcomes, including acute myocardial infarction, Bell's palsy, cerebral venous sinus thrombosis, Guillain-Barré syndrome, myocarditis/pericarditis, pulmonary embolism, stroke, and thrombosis with thrombocytopenia syndrome in the first 21 days after vaccination compared with 22 to 42 days postvaccination. The authors cautioned that for some outcomes the statistical power was limited and the confidence intervals were wide, so continued surveillance is needed. An accompanying editorial pointed out that although no studied events were increased in the population overall, the study did identify an excess risk of myocarditis/pericarditis with vaccination in those ages 12 to 39 years.

The effect of the delta variant on vaccine effectiveness was described by an analysis of more than 500,000 cases in 17 U.S. jurisdictions between April 4 and July 17, published Sept. 10 by MMWR. As the prevalence of delta rose from less than 1% to 90%, vaccine effectiveness declined from 91% to 78% for infection, from 92% to 90% for hospitalization, and from 94% to 91% for death, the study estimated. Unvaccinated patients still had 10-fold higher risk of hospitalization and death, the study authors noted. accompanying multistate analysis of 32,867 hospital and urgent care encounters in June to August estimated the vaccines to be 86% effective against hospitalization, while a February to August analysis from Veterans Affairs medical centers found vaccination to be 87% effective against hospitalization. All three studies found indications of lower vaccine effectiveness in older patients. The effectiveness of the mRNA vaccines before delta was calculated using more than 63,000 hospital, ED, and urgent care visits from Jan. 1 through June 22, 2021, in a study published by the New England Journal of Medicine on Sept. 8. It found that the vaccines were 89% effective against hospitalization, 90% effective against ICU admission, and 91% effective against infection leading to an ED or urgent care clinic visit.