Nearly half of the free Covid-19 tests made available by the Biden administration remain unclaimed, FDA increases the dosage of the monoclonal antibody Evusheld to combat omicron subvariants, and more in this week's roundup of Covid-19 news.

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• A preprint study from the New York State Department of Health (NYSDOH) suggests that Pfizer-BioNTech's Covid-19 vaccine is substantially less protective against infection and hospitalization in children ages 5-11. For the study, researchers examined data from 365,502 children ages 5-11 (23.4%) and 852,384 children ages 12-17 (62.4%) who were fully vaccinated between Dec. 13, 2021, and Jan. 30, 2022. Overall, the researchers found that, while vaccine effectiveness against infection decreased from 66% to 51% in children ages 12-17, the drop was much steeper in children ages 5-11, going from 68% to just 12%. In addition, protection against hospitalization dropped from 100% to 48% in children ages 5-11, compared with the drop from 85% to 73% in older children. The study's authors hypothesized that the decreased protectiveness in children ages 5-11 may be due to the smaller vaccine dose they receive in comparison to children ages 12-17. Children ages 5-11 only receive a 10-milligram dose of the vaccine, a third of the dose given to individuals ages 12 and older. According to Rosenberg, the study's findings ultimately underscore the need for more information on the best dose, number, and timing for the vaccines given to children. (Mandavilli/Weiland, New York Times, 2/28; Walker, MedPage Today, 2/28; Branswell, STAT News, 2/28; Romo/Stein, NPR, 2/28)

• Nearly half of the 500 million free Covid-19 tests made available to the public by the Biden administration have not been claimed, AP/Modern Healthcare reports. According to federal officials, there are fewer than 100,000 orders a day for the tests now that Covid-19 case counts are decreasing and people feel less urgency to test. Of the tests that have been ordered, 40% have gone to Americans in "high vulnerability ZIP codes" or low-income areas. Despite this decrease in demand, federal officials say the program will help build a deeper, more elastic testing infrastructure that will help accommodate potential future surges. "We totally intend to sustain this market," said Tom Inglesby, testing advisor to the Covid-19 response team. "We know the market is volatile and will come up and down with surges in variants." (AP/Modern Healthcare, 2/27; AP/Modern Healthcare, 3/1)

• The Pentagon's Defense Innovation Unit (DIU) last week awarded Philips Healthcare a contract to lead DIU's Covid-19 health monitoring project. According to Politico, the Pentagon has spent the past two years designing an algorithm that is used with "predictive bio-wearables" technology, such as a wristwatch, to track people's health and alert them to a potential coronavirus infection days before they are symptomatic. The algorithm calculates a score between one and 100 based on a user's collected data, and the higher the score, the higher the likelihood of infection. Previously, DIU tracked 11,500 participants from June 2020 to September 2021, and preliminary results showed that the algorithm's projected accuracy was around 82%, with a false positive rate of 11% over a 14-day period. Through the partnership with Philips, the program will track 200 users for one year, and DIU is in talks with the Defense Health Agency and HHS to gauge interest and potentially gain more users. (Hudson, Politico, 2/23)

• FDA last week announced that it revised the emergency use authorization of AstraZeneca's monoclonal antibody treatment Evusheld to increase its initial dosing regimen from 150 mg to 300 mg. According to MedPage Today, Evusheld is intended as a preventative treatment against coronavirus infection for individuals ages 12 and older who are moderate-to-severely immunocompromised and may not generate a strong response to vaccination. It can also be used by those who are allergic to components of the Covid-19 vaccines. This change in dosing was made based on data suggesting a higher dose might be needed to prevent infection from two omicron subvariants, FDA said. In addition, the agency said the treatment interval, which was initially set at once every six months, may need to be shortened to around three months in the future. "The duration of protection provided by Evusheld ... may not be as long as was shown in the clinical trial supporting the initial authorization because the clinical trial data came from a time period before the emergence of the BA.1 and BA.1.1 subvariants," FDA wrote. (Walker, MedPage Today, 2/25)

• Walmart last week announced that 80% of the Covid-19 vaccines its store administered were in "medically underserved" areas of the United States—underscoring the retailer's efforts to expand its health care services. According to Walmart, 4,000 of its 5,100 stores are in urban or rural areas that are considered "medically underserved" by the Health Resources & Services Administration, which means they don't have enough access to health care services, Forbes reports. To promote Covid-19 vaccination in these communities, the company implemented a "Get Out the Vaccine" campaign that partnered with various organizations to provide people with information about Covid-19 and the importance of vaccination. Overall, 43% of people who received their Covid-19 vaccination from a Walmart pharmacist or pharmacy technician were "new or inactive" patients, meaning they had not received health care services at the retailer before. "The simple things are where you start," said Cheryl Pegus, Walmart's EVP of health and wellness. "This is a trust touching-human business. We have spent a lot of time building up community relationships." (Japsen, Forbes, 2/23)