Respiratory Diseases Roundup

COVID Vaccine Delays, Pediatric Flu Gaps, and Reproductive Effects of SARS-CoV-2

Miranda Manier, BA

Key Highlights

  • New rules from United States Department of Health and Human Services (HHS) could delay updated COVID-19 shots until after fall 2025.
  • Clinicians diverge widely in prescribing oseltamivir to hospitalized children with influenza.
  • SARS-CoV-2 infection is linked to decreased sperm count, motility, and DNA integrity.
  • Influenza and COVID-19 vaccines slightly lengthen menstrual cycles—temporarily and only if given during the follicular phase.

Regulatory Shift May Delay Fall COVID Vaccine Rollout1

A policy change under HHS Secretary Robert F. Kennedy Jr. may delay updated COVID-19 vaccines from Pfizer and Moderna. The new approach requires that all vaccines—if deemed “new products” by the FDA—undergo placebo-controlled clinical trials, even if they use the same formulation with minor updates. This contrasts with the previous model, which permitted modified vaccines to bypass large-scale trials based on immunogenicity data, similar to the annual flu shot model. Experts warn that the new requirements could prevent sufficient vaccine doses from being manufactured in time for fall 2025 distribution.

Vaccine developers typically receive guidance in the spring on which strain to target, leaving limited time to produce and distribute the updated shots. If the FDA categorizes the fall 2025 COVID-19 vaccines as new products, companies will need to design, recruit for, and conduct new trials, which could delay rollout by several months. Critics, including FDA advisors and leading vaccine researchers, argue the changes are not evidence-based and may restrict access to life-saving vaccines. They also raised ethical concerns over conducting placebo-controlled trials when effective vaccines are already available. The FDA has already postponed approval of Novavax’s reformulated COVID-19 vaccine due to these new rules.

Antiviral Prescribing for Pediatric Influenza Varies Widely2

A cross-sectional survey across seven US children’s hospitals revealed significant variability in pediatricians’ prescribing of oseltamivir for hospitalized children with influenza, despite national guidelines recommending antiviral use in all such cases. Surveying 787 pediatric clinicians across five specialties, researchers found that oseltamivir was recommended in only 49.5% of clinical vignettes consistent with 2023 American Academy of Pediatrics (AAP) treatment criteria. Treatment rates varied by institution (43.5% to 64.2%) and specialty, with infectious disease physicians recommending treatment in 70.9% of scenarios compared with 41.6% among hospitalists.

Factors associated with lower likelihood of recommending antivirals included longer symptom duration and reduced need for oxygen support. Awareness of the AAP recommendations increased the probability of treatment; however, even among informed clinicians, oseltamivir was withheld in 38% of applicable cases. A substantial majority (87.4%) of respondents supported the need for a randomized controlled trial to better evaluate antiviral efficacy in hospitalized children.

SARS-CoV-2 Infection Associated With Sperm Quality Decline3

A dual cross-sectional and longitudinal study conducted in China found that SARS-CoV-2 infection was associated with declines in sperm quality, including reductions in sperm count, motility, and increased DNA fragmentation. Among 604 participants in the cross-sectional arm, those who had recovered from COVID-19 showed significantly lower total sperm count and motility and higher DNA fragmentation index (DFI) compared with uninfected controls. In the longitudinal cohort of 140 men with pre- and post-infection semen samples, the decline in semen quality persisted after infection, while 149 COVID-negative controls showed stable or improved parameters.

Specifically, 71.4% of COVID-19–positive patients demonstrated a drop in Grade A motility, 69.3% in total motility, and 75% showed elevated DFI. The observed declines were statistically significant and not explained by confounding environmental or seasonal factors, as the control group underwent analysis during the same timeframe. Researchers noted that the impact of COVID-19 was most pronounced in parameters closely tied to fertility potential and highlighted the importance of integrating SARS-CoV-2 screening into fertility assessments. While the long-term reversibility of these changes remains uncertain, the findings suggest a transient but potentially clinically relevant impairment in male reproductive health following SARS-CoV-2 infection.

Influenza and COVID-19 Vaccines Linked to Minor Menstrual Changes4

A global cohort study of 1501 individuals with regular menstrual cycles found a small, temporary increase in cycle length following influenza vaccination, either alone or when coadministered with a COVID-19 vaccine. Participants using a digital birth control application contributed menstrual data from three cycles before vaccination and at least one cycle afterward. The mean cycle length increased by 0.40 days for those receiving influenza vaccine alone and 0.49 days for those receiving both vaccines, with no significant differences between groups. Changes were only significant when vaccination occurred during the follicular phase.

Among those vaccinated, 4.7% (influenza only) and 5.9% (coadministration) experienced a cycle length increase of greater than or equal to 8 days. These changes resolved by the postvaccination cycle. Sensitivity analyses excluding individuals with hormonal or reproductive conditions did not alter the results.

References

  1. Lovelace, Berkley Jr. Updated Covid vaccines for the fall may be in jeopardy under Kennedy's new rules. NBC News. May 1, 2025. Accessed May 13, 2025. https://www.nbcnews.com/health/health-news/updated-covid-vaccines-fall-may-jeopardy-rfk-jrs-new-rules-rcna204242
  2. Bassett HK, Rao S, Beck J, et al. Variability of clinician recommendations for oseltamivir in children hospitalized with influenza. Pediatrics. 2025;155(5):e2024069111. doi:10.1542/peds.2024-069111
  3. Yuan L, Sun W, Dong Z, et al. COVID-19 infection was associated with poor sperm quality: a cross-sectional and longitudinal clinical observation study. Sci Rep. 2025;15(1):11380. doi:10.1038/s41598-025-94570-5
  4. Boniface ER, Darney BG, van Lamsweerde A, Benhar E, Alvergne A, Edelman A. Menstrual cycle length changes following vaccination against influenza alone or with COVID-19. JAMA Netw Open. 2025;8(4):e257871. doi:10.1001/jamanetworkopen.2025.7871