A study finds coronavirus vaccination does not negatively affect in vitro fertilization (IVF) outcomes, the estimated cost of preventable hospitalizations among the unvaccinated is more than $13 billion, and more in this week's roundup of Covid-19 news.

• Pfizer-BioNTech and Moderna this week announced that they have started clinical trials of omicron-specific versions of their respective Covid-19 vaccines. Pfizer-BioNTech began its clinical trial, which will involve up to 1,420 participants across three cohorts, on Tuesday. In the first cohort, people who have received two doses of the company's vaccine will receive either one or two doses of the omicron vaccine. In the next cohort, people who have received three doses will receive either another dose of the same vaccine or a dose of the omicron vaccine. And in the last cohort, unvaccinated participants will receive three doses of the omicron vaccine. According to Pfizer, the initial study results are expected in the first half of the year. Separately, Moderna on Wednesday began a clinical trial for its own omicron-specific vaccine, which will include around 600 participants. In one group, participants will receive a booster dose of the omicron vaccine at least six months after their primary Moderna series. In the other groups, participants who have already received a booster will receive the omicron vaccine at least three months after the booster. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said he believes "it's prudent to at least prepare for the possibility that [omicron] may be a persistent variant that we might have to face," but that "[w]e may not need it" since booster doses of the currently available vaccines are providing sufficient protection, particularly against hospitalization and death. (Dress, The Hill, 1/26; Loftus, Wall Street Journal, 1/26; Axios, 1/25; Herper, STAT News, 1/25; Hopkins, Wall Street Journal, 1/25; Breslin, The Hill, 1/25)

• FDA on Monday announced it is limiting the use of two monoclonal antibody treatments from Eli Lilly and Regeneron since data shows they are "highly unlikely" to be effective against the currently dominant omicron variant. According to CDC data, omicron accounted for 99% of Covid-19 cases in the United States as of Jan. 15. In a statement, FDA said it revised the authorizations for the two drugs "to limit their use to only when the patient is likely to have been infected with or exposed to a variant that is susceptible to these treatments." However, the agency said it would consider updating the drugs' authorizations if they prove to be effective against future variants. According to the Wall Street Journal, both drugs were effective against previous variants, but early testing has suggested that they are unlikely to work against omicron, which has several mutations on the spike protein the drugs targeted. Both Eli Lilly and Regeneron have previously announced that they are working to develop new antibodies that specifically target omicron. In the meantime, FDA said several other Covid-19 treatments that are likely to be effective remain available, including Vir Biotechnology and GlaxoSmithKline's antibody treatments and antiviral pills from Pfizer and Merck—although providers have noted supplies of some of these drugs are currently limited. (Weixel, The Hill, 1/25; Falconer, Axios, 1/25; Walker, Wall Street Journal, 1/24; AP/Modern Healthcare, 1/24; Jewett, New York Times, 1/24)

• Covid-19 vaccination was not associated with adverse outcomes in IVF patients, according to a recent study published in Obstetrics & Gynecology. For the study, researchers analyzed patients who underwent controlled ovarian hyperstimulation or frozen embryo transfer at one academic medical center from February to September 2021. In total, there were 222 vaccinated and 983 unvaccinated patients in the ovarian hyperstimulation group, and 214 vaccinated and 733 unvaccinated patients in the embryo transfer group. Overall, the researchers found that both vaccinated and unvaccinated patients had similar fertilization rates (80.7% vs. 78.7%) and clinical pregnancy rates (59.5% vs. 63.7%). In addition, Covid-19 vaccination was not associated with any other negative IVF or pregnancy outcomes, such as number of eggs retrieved or rates of early pregnancy loss. "The vaccine did not have any harmful impact on fertility treatment outcomes or early pregnancy outcomes in our patients," said Devora Aharon, the study's lead author from the Icahn School of Medicine at Mount Sinai. Separately, Eve Feinberg, a reproductive endocrinologist at the Northwestern School of Medicine, who was not involved in the study, said "[t]his is really convincing evidence that shows that on a fundamental level—the microscopic level—of human reproduction, vaccines do not have any negative effect." (D'Ambrosio, MedPage Today, 1/26)

• Covid-19 hospitalizations among unvaccinated adults cost billions of dollars from June through November 2021, according to an analysis from the Kaiser Family Foundation (KFF). For the analysis, researchers examined data of confirmed adult Covid-19 hospitalizations from HHS and data of Covid-19 hospitalizations among vaccinated individuals from CDC. Overall, they estimated that there were 690,000 preventable Covid-19 hospitalizations among the unvaccinated between June and November 2021. Using an average Covid-19 hospitalization cost of $20,000, the researchers estimated the costs of preventable Covid-19 hospitalizations among the unvaccinated to be $13.8 billion in that six-month period. However, they noted this figure is likely an underestimate since it does not include the cost of outpatient treatment, which could also be substantial. "The monetary cost of treating unvaccinated people for Covid-19 is borne not only by patients but also by society more broadly, including taxpayer-funded public programs and private insurance premiums paid by workers, businesses and individual purchasers," KFF said. (Plescia, Becker's Hospital CFO Report, 1/10; Amin/Cox, PETERSON-KFF Health System Tracker, 12/22/21)

• CDC on Wednesday reached out to pharmacists to reiterate that immunocompromised individuals are eligible for a fourth Covid-19 vaccine dose. Previously, Kaiser Health News reported that some immunocompromised individuals seeking fourth doses were being turned away by pharmacy employees who were unfamiliar with CDC's latest booster guidelines. The agency initially recommended four vaccine doses for immunocompromised people in October, and since then, it has been working to educate pharmacists and other providers. According to Eric Topol, founder and director of the Scripps Research Translational Institute, CDC's outreach to pharmacists about the booster guidelines "should have been done many weeks ago," but he is "glad that the White House team is finally pushing forward on this." (Szabo, Kaiser Health News, 1/26; Szabo, Kaiser Health News, 1/25)