COVID-19 update 2023: Cases declining but so has detection; booster recommendations given
Presenter: Carlos del Rio, MD, Emory University School of Medicine, Atlanta.
COVID-19 Update 2023: Where Are We Now? Presented April 28, 2023
An update on COVID-19 infection rates and vaccine and treatment efficacy was provided by Carlos Del Rio, MD, Emory University School of Medicine, Atlanta.
As of February 2023, the total number of COVID-19 cases reported globally was 671 million, with close to 7 million deaths. Currently, more than 1,000 deaths attributed to COVID-19 are reported daily, down from about 14,000 daily at the peak of the pandemic. “The number of deaths from COVID doesn't reflect the true burden of disease,” he said. “When you look at excess deaths, the global estimate is about 20 million,” with excess deaths defined as the number of deaths above the typical from a given year.
While the number of weekly COVID-19 cases has declined, so has detection, attributable in part to individuals testing themselves at home and not reporting the outcome, he said. “You cannot track just the number of positive cases because the number of positive cases comes from laboratory testing; it doesn’t come from where most people are getting tested nowadays,” he said. Other means of tracking the direction of COVID-19 infections may be needed, such as the number of rapid tests being sold at drugstores.
Data from 96 million COVID-19 cases in the United States show a steep increase in COVID-19-related mortality at age 50 and beyond, with the death rate increasing with increasing age. By ethnicity, the number of cases, hospitalizations, and deaths due to COVID-19 is highest among American Indian or Alaskan Native, Non-Hispanic persons.
In rural America, COVID has hit Black and Hispanic people hardest, he said. At the peak of the Omicron wave, COVID killed Black Americans in rural areas at a rate roughly 34% higher than it did white people.
“One of the things that has happened with this virus is how quickly it has evolved and how quickly the different variants have changed and taken over prior variants,” said Dr. del Rio. “What you find is that alpha and delta are variants that have much higher intrinsic fitness. But what you also find is that Omicron and the subsequent variants after Omicron, which are Omicron derivatives, have higher fitness in the context of immune escape, with much higher transmissibility. So as we are more and more immune, the immunity doesn’t protect you from infection; it protects you from severe disease and death.”
Vaccine performance
As with many other respiratory viral vaccines, it was known from the beginning that a COVID-19 vaccine would not be effective at preventing infection. Vaccine efficacy is a measure of how well a vaccine protects against outcomes such as infection, symptomatic illness, hospitalization, and death, he reminded. Clinical trials of COVID-19 vaccines were not designed with the goal of preventing infection but rather preventing severe disease. More than 20 million lives were saved last year by COVID vaccines, he estimated.
The durability of protection against severe disease from mRNA vaccine-induced immunity is more than twice that with an acquired infection. “But we see waning immunity regardless of which vaccine you receive,” he said. The waning protection against severe disease is more mild than the waning protection against acquired infection. Because of immune escape from either vaccination or infection, herd immunity is probably not achievable.
For now, a fourth dose of vaccine (second booster dose) 4 to 6 months after a third shot is advised for people 50 years old and older, immunocompromised people, people younger than 50 years with multiple comorbidities, frontline health care workers, and essential workers. Boost later in the young and healthy and those with hybrid immunity with infection in the past 6 months.
Treatment
Nirmatrelvir-ritonavir is authorized for treatment of mild to moderate COVID in adult and pediatric patients who are at high risk of progression and within 5 days of symptom onset. COVID-19 viral load is reduced by about 10-fold in nirmatrelvir-ritonavir recipients at day 5 relative to placebo, resulting in an 88% reduction in hospitalization or death in unvaccinated nonhospitalized patients at high risk for progression to severe COVID-19. Dosing is twice daily for nirmatrelvir (2 tablets, each containing 150 mg) plus 1 tablet of 100 mg of ritonavir daily for 5 days with or without food. In patients with moderate renal insufficiency (estimated glomerular filtration rate ≥ 30 but < 60 mL/min/1.73 m2), the recommended regimen is a single 150-mg tablet of nirmatrelvir plus 100 mg of ritonavir twice daily for 5 days.
This combination is not recommended for patients with severe renal insufficiency or severe hepatic impairment. Because ritonavir inhibits the CYP3A4 enzyme, it should not be administered with certain medicines including amiodarone, clopidogrel, rifampin, and rivaroxaban. Calcineurin inhibitors may need to be held or the dosage markedly reduced. Atorvastatin and rosuvastatin may be temporarily stopped in patients taking ritonavir.
Molnupiravir was found to reduce the rate of hospitalization and death by 30% compared with placebo in nonhospitalized unvaccinated adults with mild to moderate COVID-19. In a separate study, time to recovery was faster in patients randomized to molnupiravir compared with usual care (9 vs 15 days) and the median viral load was lower in the molnupiravir arm. Molnupiravir is authorized for adults with mild to moderate COVID at high risk for progression and within 5 days of symptom onset only if other treatments are not accessible or clinically appropriate. It is not recommended during pregnancy and not authorized for children. Men of reproductive potential should use contraception during treatment and for 3 months after the last dose.
“It’s very encouraging to see that [molnupiravir] is the one drug that appears to decrease the duration of symptoms and may decrease the viral load, which obviously would be important for transmission,” said Dr. del Rio.
Remdesivir resulted in an 87% reduction in the rate of hospitalization relative to placebo in a randomized trial of high-risk unvaccinated nonhospitalized patients who were 7 or more days after symptom onset. It is approved by the US Food and Drug Administration for use in adults and children with COVID-19 infection. Remdesivir is administered for 3 days via intravenous infusion. “If you can arrange to have it delivered to the patient’s home and do it through an IV infusion company, it works great and it’s a very easy infusion to give over 3 days,” he said.
References
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Disclosures
Carlos del Rio, MD, has no relationships with entities whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients.