A new cost-effective Covid-19 vaccine shows positive results in early trials, Defense Secretary Austin Lloyd reasserts the necessity of vaccination for service members, and more in this week's roundup of Covid-19 news.

Your top resources on the Covid-19 vaccines

• According to several experts, long Covid may be exacerbating America's current labor shortage—and the problem could continue for years, as people struggle with lingering Covid-19 symptoms. Although the prevalence of long Covid is not known, the American Academy of Physical Medicine and Rehabilitation estimates around 30% of Covid-19 patients—more than 22 million Americans—may be suffering from long Covid. Furthermore, Kate Bach, a nonresident senior fellow at the Brookings Institution, said roughly 1.6 million workers may be currently out of the labor market due to long Covid, accounting for 15% of unfilled jobs. "It's critical we start measuring this pandemic not just in hospitalizations and deaths, but in disability," said Charlie McCone, a 32-year-old long Covid patient. "[I]t's going to have an enormous impact on the workforce and already is." (Reed/Peck, Axios, 2/3)

• During the omicron wave, unvaccinated adults had a significantly increased risk of hospitalization from Covid-19 compared with those who were vaccinated and boosted, according to a new CDC study. The researchers analyzed data on Covid-19 incidence and hospitalization rates in Los Angeles County from Nov. 7, 2021, to Jan. 8, 2022. Overall, unvaccinated adults were 3.6 times more likely to be infected and 23 times more likely to be hospitalized compared with vaccinated and boosted adults. Similarly, compared with adults who had been vaccinated but not boosted, unvaccinated adults were twice as likely to be infected and 5.3 times more likely to be hospitalized. "Efforts to promote Covid-19 vaccination and boosters are critical to preventing Covid-19-associated hospitalizations and severe outcomes," the authors wrote. "Ongoing Covid-19 surveillance with data linkages to vaccination ... are critical for monitoring vaccine effectiveness and increased protection from boosters, particularly during the omicron predominant period." (Reyes, Axios, 2/1; Sullivan, The Hill, 2/1)

• A new preprint study published in bioRxiv suggests that an intranasal Covid-19 vaccine could be effective as a booster dose to strengthen waning immunity. Using a "prime and spike" strategy, the researchers administered a nasal vaccine containing purified versions of the coronavirus's spike protein to mice who had previously received two doses of Pfizer-BioNTech's vaccine. They found that the nasal vaccine strongly boosted antibodies and immune memory cells in the nose and throat. Furthermore, the mice had lower-than-expected viral loads, which could help reduce viral transmission. In comparison, the nasal vaccine had no effect on mice who had not been "primed" with an mRNA vaccine, since it builds on what the immune system has already learned. "This strategy is likely to confer long-lasting and cross-reactive memory that can be quickly restimulated to prevent viral spread," said Akiko Iwasaki, an immunologist at Yale University who led the study. "The intranasal spike protein booster will also be much easier to administer (via nasal spray) ... and is much more likely to be accepted by people who are hesitant of mRNA or those with needle phobia." (Lapid, Reuters, 1/28; Mandavilli, New York Times, 2/2)

• Researchers at the Icahn School of Medicine at Mount Sinai have developed a Covid-19 vaccine that could be manufactured like a flu shot, Reuters reports. The vaccine, which is called NDV-HXP-S, uses an engineered version of the Newcastle disease version with embedded coronavirus spike proteins. In an early clinical trial, the researchers found that NDV-HXP-S produced proportionally more neutralizing antibodies against the coronavirus than the mRNA vaccines from Moderna and Pfizer-BioNTech. "The NDV-HXP-S vaccine induced neutralizing antibody responses against wild type (the original) SARS-CoV-2 that matched what we see after mRNA vaccination, but the proportion of neutralizing antibodies in the response was higher for NDV-HXP-S," said Florian Krammer, a professor at Mount Sinai. According to the researchers, their vaccine can be manufactured at a low cost in chicken eggs, similarly to flu vaccines, a capability that would enable low- and middle-income countries to manufacture the vaccine locally. Currently, early clinical trials with a live version of the vaccine are ongoing in Mexico and the United States, while an inactivated version is being tested in Brazil, Thailand, and Vietnam. (Lapid, Reuters, 1/28)

• Defense Secretary Lloyd Austin this week sent letters to seven governors who opposed Covid-19 vaccination requirements for National Guard members. According to Austin, vaccination is necessary because the coronavirus "takes our service members out of the fight, temporarily or permanently, and jeopardizes our ability to meet mission requirements." He added, "To ensure that we maintain a healthy and ready military force capable of accomplishing our mission to defend this nation and to protect the American people, vaccination against Covid-19 is an essential military readiness requirement." All service members, including the National Guard, were required to be vaccinated against Covid-19 beginning in August 2021. According to NPR, the vast majority of service members have been vaccinated, but military officials in December began enforcing disciplinary actions, including discharge, for noncompliant members. (Gonzalez, Axios, 2/1; Schwartz, NPR, 12/17/21)