Moderna's Covid-19 vaccine was found to be safe and effective in children ages 6 to 11, Americans can now order an additional eight free Covid-19 tests from the federal government, and more in this week's roundup of Covid-19 news.

• FDA on Tuesday authorized booster shots of Pfizer-BioNTech's Covid-19 vaccine for children ages 5 to 11, citing concerns about the omicron variant and risks of long Covid in this age group. On Thursday, CDC's Advisory Committee on Immunization Practices voted in favor of recommending boosters for this age group, and CDC director Rochelle Walensky signed off on the recommendation. "While it has largely been the case that Covid-19 tends to be less severe in children than adults, the Omicron wave has seen more kids getting sick with the disease and being hospitalized, and children may also experience longer-term effects, even following initially mild disease," said FDA Commissioner Robert Califf. Children ages 5 to 11 will be eligible for a booster dose at least five months after their two-dose primary series. However, it is unclear how much of a demand there will be for booster doses in this age group. According to CDC data, fewer than a third of children ages 5 to 11 are currently fully vaccinated, much lower than the rate in the overall population, and only a around 25% of adolescents have received a booster dose. (Walker, MedPage Today, 5/17; LaFraniere, New York Times, 5/17; Alltucker, USA Today, 5/17; Mandavilli, New York Times, 5/19; Stein, "Shots," NPR, 5/17; Choi, The Hill, 5/19)

• Over 75% of patients with long Covid were not hospitalized during their initial infection, according to a new study from FAIR Health. For the study, researchers analyzed private insurance claims data from over 78,000 people who were diagnosed with long Covid between Oct. 1, 2021, and Jan. 31, 2022. Overall, roughly 76% of long Covid patients had not been hospitalized for their infection, but experienced "abnormalities of breathing, cough, and malaise and fatigues" months after being diagnosed, the researchers wrote. In addition, around of third of long Covid patients had no pre-existing health conditions, much higher than what researchers initially expected. According to the New York Times, these findings add to growing evidence that even patients with mild or moderate Covid-19 symptoms can experience debilitating long-term symptoms. "It's generating a pandemic of people who were not hospitalized, but who ended up with this increased disability," said Paddy Ssentongo, an assistant professor of infectious disease epidemiology at Pennsylvania State University, who was not involved in the study. In the future, FAIR Health president Robin Gelurd said researchers plan to continue tracking the patients to see how long their symptoms last, as well as analyze if and when they were vaccinated. (Gonzalez, Axios, 5/18; Belluck, New York Times, 5/18)

• Covid-19 vaccination after infection was associated with a lower risk of developing long Covid, according to a new study from the United Kingdom published in BMJ. For the study, researchers examined data from 28,356 adults ages 18 to 69 who participated in the U.K.'s Covid-19 Infection Survey and had received at least one vaccine dose after being infected between February and September 2021. The mean age of participants was 46, 56% were women, and 89% were white. Overall, one dose of a Covid-19 vaccine was associated with a 12.8% lower risk of long Covid, while two doses was associated with an 8.8% reduction in risk. This reduced risk lasted an average of at least nine weeks, with a small 0.08% decrease each week. "Our results suggest that vaccination of people previously infected may be associated with a reduction in the burden of long Covid on population health, at least in the first few months following vaccination," said Daniel Ayoubkhani, one of the study's authors. "The sustained 9% fall in the odds of long Covid after the second dose — this may appear modest, but we need to remember that this is out of a sample of people from the population with and without long Covid, so the reduction among only people who had pre-existing symptoms will be larger." According to the researchers, they also plan to look at longer-term outcomes in people who already have long Covid, including those who have received booster doses and those who were infected with the omicron variant. (Cooney, STAT News, 5/18; Walker, MedPage Today, 5/18)

• FDA on Monday declined to authorize fluvoxamine, a generic antidepressant, as treatment for Covid-19, despite efforts by a small group of doctors who argued that it could be a cheap and accessible way to reduce hospitalizations and deaths. The primary evidence of the drug's potential efficacy against Covid-19 was a large, randomized, clinical trial of nearly 1,500 patients in Brazil. Patients who received fluvoxamine were 32% less likely to be hospitalized or need at least six hours of emergency care compared to patients who received a placebo. However, FDA said the data submitted failed to show sufficient evidence of fluvoxamine's use as a Covid-19 treatment. In particular, the agency said it was not sure the six-hour cutoff in the Brazil study was "a clinically meaningful threshold" and that two other large, randomized clinical trials of the drug did not find similar benefits. In a detailed rebuttal, David Boulware, an infectious disease physician from the University of Minnesota who has led the effort to authorize fluvoxamine, said FDA's reasoning in its rejection was "inconsistent." He added that several clinical trials of fluvoxamine are still ongoing, and if more supporting evidence comes in, he and other researchers may submit another request for FDA authorization. (Mast, STAT News, 5/16)

• Americans can now order an additional eight free rapid antigen tests from the federal government, bringing the total number of tests offered by household to 16, NPR reports. "As the highly transmissible subvariants of Omicron drive a rise in cases in parts of the country, free and accessible tests will help slow the spread of the virus," a White House fact sheet said. The program, which launched in January, first offered four free tests before allowing people to submit a request for an additional four tests in March. In the first four months of the program, the White House said 350 million tests have been delivered in 70 million households, or more than half of all households in the United States. To order this new round of free tests, people can visit COVIDtests.gov. The tests can also be ordered through a hotline, 1-800-232-0233, for those who cannot place an order on the website. (Tyko, Axios, 5/16; Keith, NPR, 5/16)

• Moderna's Covid-19 vaccine was safe and effective for children ages 6 to 11, according to an interim analysis of a Phase II/III trial. In the trial, which took place from March to August 2021, 2,998 participants received two 50 μg doses of the vaccine, half of the adult dose, 28 days apart, while 973 participants received a placebo. The mean age of the participants was 9 years, and 51% were boys. In a modified intention-to-treat population, the estimated vaccine efficacy in this age group was 88% against symptomatic infection, primarily from the delta variant, at two weeks or longer after the first shot. The most common side effects were headache and fatigue, with chills and fevers more common after the second shot than the first. According to the trial's researchers, the "findings suggest that this vaccine provides a protective benefit for children against variants of concern" since the trial took place during the delta wave. Last week, Moderna requested FDA authorize the use of its vaccine in this age group. Currently, FDA is reviewing the company's data on adolescents, as well as younger children, and is expected to make a decision about the vaccine for children of all ages in June. (Walker, MedPage Today, 5/11; Mandavilli, New York Times, 5/11)