The Vaccine Intelligence Report: April 22-28

The Vaccine Intelligence Report—brought to you by Vaccinate Your Family—provides clear, fact-based updates on vaccine policy, research, and public health each week. This report is part of Viral Truths, a resource designed to cut through the noise, offering concise information to help navigate the evolving immunization landscape.

THIS WEEK AT A GLANCE

  • The Trump Administration has moved to pause the vaccine policy lawsuit brought by leading medical organizations, while reverting the CDC’s website to prior immunization schedules, leaving federal vaccine guidance in a holding pattern
  • Lawmakers from both parties pressed HHS Secretary Robert F. Kennedy Jr. on vaccine policy during a series of congressional hearings last week, questioning him on shifting measles messaging and raising concerns about public health communication
  • Federal officials blocked publication of a CDC study showing the benefits of Covid vaccination, citing methodological concerns that experts say rely on standard, widely used approaches, and raised questions about internal review processes
  • New research reinforces the benefits and safety of maternal vaccination, showing strong protection against RSV in infants and no added risk from coadministration of flu and pertussis vaccines during pregnancy
  • State vaccine policy activity continues nationwide, with Connecticut and New York advancing measures to strengthen access and state authority, while Arizona moves forward with “medical freedom” bills, and Florida declines to take up vaccine legislation during a special session
  • Measles activity remains elevated nationwide, with new cases reported across multiple states, even as South Carolina declares the end of its largest outbreak in decades
  • Respiratory illness activity remains low overall, but rotavirus cases continue to rise, as experts emphasize the importance of vaccination

NEED TO KNOW

Administration Seeks Pause in Vaccine Lawsuit as Vaccine Recommendation Resets Take Effect

  • New developments have emerged following the March 16 court ruling in a lawsuit brought by leading medical organizations, which has temporarily blocked changes to the recommended childhood immunization schedule and to the Advisory Committee on Immunization Practices (ACIP).
  • In response to the ruling, the Centers for Disease Control and Prevention (CDC) reverted to the July 2, 2025 version of the childhood and adolescent immunization schedule—effectively restoring prior recommendations and reversing more recent changes, at least for now.
    • That said, the May 2025 policy shifting Covid vaccination to shared clinical decision-making (SCDM) for healthy individuals ages 6 months and older—including those who are pregnant—remains in place.
    • CDC also updated the Vaccines for Children (VFC) resolutions, restoring program recommendations in line with the July 2025 schedule.
  • At the same time, the federal government requested (Apr. 23) that the court pause proceedings while it considers whether to appeal the ruling.
    • If granted, the pause would halt further filings and potential discovery as the Administration evaluates next steps.
    • The Administration currently has until mid-May to decide whether to move forward with an appeal.
  • While the request was framed as a procedural step, it comes amid broader signals that the Administration may be seeking to downplay vaccine-related policy actions before the midterm elections as scrutiny from lawmakers, courts, and the public continues to grow.
  • Taken together, these developments leave current vaccine policy in a holding pattern—restoring prior guidance in the near term while longer-term decisions on the immunization schedule and ACIP’s future remain unresolved.

Lawmakers Press Kennedy on Vaccine Policy as Hearing Series Wraps 

  • Last week, Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. concluded a series of seven Congressional hearings tied to the Administration’s FY2027 budget request, with final appearances before the House Energy and Commerce and Senate Appropriations health subcommittees (Apr. 21), and the Senate Finance and Health, Education, Labor, and Pensions (HELP) Committees (Apr. 22).
  • Lawmakers across both parties—including two Republican physicians—pressed Kennedy on vaccine policy and public health messaging.
    • Senator Dr. John Barrasso (R-WY), Majority Whip and former surgeon, told Kennedy “it’s very hard to keep up with” shifting vaccine guidance and urged Kennedy to ensure recommendations are “clear, evidence-based and trustworthy.”
    • Senator Dr. Bill Cassidy (R-LA), who has repeatedly clashed with Kennedy, warned that “the [vaccine] trust gap has worsened over the last year due to false statements about safety and efficacy of vaccines for preventable diseases like measles.”
  • In a notable shift from prior remarks, Kennedy repeatedly voiced support for the measles, mumps, and rubella (MMR) vaccine.
    • In an exchange with Senator Michael Bennet (D-CO), Kennedy affirmed that HHS “[promotes] the measles vaccine,” noting it “prevents measles in 97 percent of the people who take it.” He also stated that HHS has “advised every child to get the MMR.”
    • These comments mark a departure from Kennedy’s earlier statements, in which he encouraged parents to “do [their] own research” and raised concerns about the vaccine’s safety.
  • Despite this shift, Kennedy downplayed the broader role of vaccines in improving public health, arguing that hygiene and sanitation were the primary drivers of declining mortality in the 20th century.
    • Cassidy pushed back, noting that the American Academy of Pediatrics (AAP) source Kennedy cited states that vaccines introduced in the 20th century “virtually eliminated” deaths from diseases such as polio and measles.
  • Kennedy also committed to responding to a request from Senator Ron Johnson (R-WI) regarding a leaked memo from the Food and Drug Administration (FDA) alleging that 10 children died due to Covid vaccination. The memo, which did not include details to support its findings, has been widely criticized.
    • Johnson—who has a history of criticizing vaccines—chairs the Senate Homeland Security and Governmental Affairs investigations subcommittee, which is holding a hearing on Covid vaccine safety signals today (Apr. 29).
  • Kennedy offered mixed signals on how he would work with CDC Director nominee Dr. Erica Schwartz if confirmed.
    • He told Cassidy that he would allow Schwartz to make decisions independently of political appointees.
    • However, in an exchange with Representative Raul Ruiz (D-CA), Kennedy declined to commit to implementing CDC vaccine guidance without interference, stating he was “not going to make that kind of commitment.”
  • The exchanges underscore continued uncertainty around how vaccine policy will be shaped and implemented under Kennedy’s leadership, particularly as key decisions on CDC leadership, ACIP, and federal guidance remain unresolved.

CDC Blocks Publication of Study Showing Covid Vaccine Benefits

  • The study, conducted with CDC scientists, found that vaccination reduced Covid-related emergency visits by 50% and hospitalizations by 55% among adults during the most recent winter season.
  • The decision to block the report was made by Dr. Jay Bhattacharya—who is currently leading the CDC—after he cited concerns about the study’s methodology.
    • Reportedly, specific concerns were raised around the study using observational data as the means for evaluating vaccine effectiveness, meaning how well the vaccine worked was calculated based on differences in outcomes between vaccinated and unvaccinated individuals who sought care for Covid—relying on real world patient data rather than a randomized trial.
  • Experts have pushed back on this justification for blocking publication, noting that this approach is widely used and well-established for evaluating vaccines against respiratory viruses, including Covid and influenza (flu), and has been used in prior studies published in MMWR.
    • Notably, similar methods were used in a recent flu vaccine effectiveness study that was published without issue, raising questions about the consistency of the standard being applied.
    • Further, this type of real-world analysis is commonly used when evaluating vaccines that are already widely available, as randomized control trials in these instances would require withholding an available, effective vaccine from control groups, putting trial participants at unnecessary risk and jeopardizing public health—a violation of ethical and scientific standards.
  • Additionally, policymakers and public health leaders have also raised concerns about the decision to block a report after it had already cleared internal scientific review, questioning whether the rationale reflects a departure from longstanding scientific processes.
    • While agencies routinely review scientific studies before publication, former CDC officials note that it is highly unusual for a report to be blocked at this stage after clearing scientific review and being scheduled for release.

New Studies Reinforce Benefits and Safety of Maternal Vaccination 

  • Two new studies add to the evidence base for maternal vaccination, showing that respiratory syncytial virus (RSV) vaccination for pregnant women can substantially reduce infant hospitalizations and underscoring the safety of receiving flu and pertussis vaccines on the same day during pregnancy.
  • A large real-world cohort study in the U.K. found that maternal RSV vaccination reduced infant hospitalizations by about 80% when given at least two weeks before birth.
    • The study, which used linked national health and vaccination data across hundreds of thousands of infants, provides robust evidence of vaccine effectiveness during the first months of life.
  • A population-based cohort study in Australia found no increased risk of adverse pregnancy, birth, or newborn outcomes when pregnant women received flu and pertussis vaccines on the same day, known as coadministration.
    • Researchers compared nearly 7,000 pregnant women who received both vaccines on the same day at 20 weeks gestation or later with a matched group who received pertussis vaccine alone.
    • The findings support coadministration as a practical way to improve maternal vaccine uptake while maintaining safety.

STATE POLICY SPOTLIGHT

New York Legislators Advance Several Bills to Strengthen Vaccine Access

  • New York lawmakers are advancing a slate of bills aimed at reinforcing vaccine access and shifting more authority over immunization policy to the state level and reducing reliance on federal guidance.
    • A10711, which has passed both the Assembly and Senate, would align childhood immunization requirements with standards set by the state health commissioner, allowing the state to rely on guidance from major medical organizations in addition to federal recommendations.
  • Additional bills would expand coverage, reporting, and protections tied to vaccination.
    • A10710 (Assembly-passed; pending in the Senate) would require insurers to cover vaccines recommended by the state or leading medical organizations—ensuring coverage extends beyond federal guidance alone.
    • A765 (Assembly-passed; pending in the Senate) would shift the state’s adult immunization registry to an opt-out system, a move expected to increase participation and improve data completeness.
  • Other proposals focus on specific settings and access points for vaccination.
    • A3254-A and A9140, both reported out of the Assembly Health Committee, would require vaccination for children attending overnight and day camps and provide legal protections for individuals administering vaccines, respectively.
    • A2078 (Assembly-passed; pending in the Senate) would require certain college students to be vaccinated against hepatitis B.

Connecticut Finalizes Vaccine Authority Bill; Polling Shows U.S. Voters Favor Candidates Who Support Vaccine Access

  • On Monday (Apr. 27), Connecticut Governor Ned Lamont signed legislation (HB 5044) expanding the state’s authority over vaccine policy, following the bill’s approval in both chambers.
    • The law allows the state to set vaccine standards and limits the application of the state’s religious freedom statute to school immunization requirements, a change that could affect ongoing litigation challenging the state’s 2021 repeal of religious exemptions.
    • Additionally, the bill establishes a Vaccines for Adults program intended to help uninsured or underinsured adults access free flu vaccines.
  • Recent polling underscores the broader context for these state-level actions, with roughly two-thirds of U.S. voters saying they prefer candidates who support vaccine access and want immunization decisions guided by trusted medical experts rather than political considerations.

Arizona Moves Forward with “Medical Freedom” Bills, While Vaccines Dropped from Florida Special Session 

  • In Arizona, two “medical freedom” bills are advancing through the legislature.
    • HB 2086, which would restrict vaccine and mask requirements, has passed both the House and Senate and is now awaiting final legislative action.
    • HB 2248, which would prohibit businesses, schools, and government entities from requiring people to be vaccinated, passed the Senate this week and is now in conference after Senate amendments.
  • Florida lawmakers will no longer consider vaccine legislation as planned during a special legislative session that began Tuesday (Apr. 28). Governor Ron DeSantis last week expanded the session’s scope to include “medical freedom,” but the House Speaker announced Tuesday that his members will not take up any vaccine related measures.
    • Vaccine discussions were anticipated to center around a bill to create a “conscience” exemption from school immunization requirements and restrict certain vaccine-related requirements, reviving provisions from legislation that failed to pass during the regular session.

OUTBREAK OUTLOOK

News on respiratory virus season, measles, pertussis, and other vaccine-preventable and infectious disease outbreaks.

South Carolina Measles Outbreak Ends as Several States Report First Cases of the Year

  • On Monday (Apr. 27), South Carolina declared the official end of its measles outbreak that began last October and infected 997 people—the largest U.S. outbreak since 1991. The last outbreak case was reported on March 15.
    • State officials reported that in total, outbreak cases and exposures affected 33 schools and 874 students and cost the state an estimated $2.1 million.
    • Officials reported that from 2025 to 2026, MMR vaccinations in Spartanburg County (the outbreak’s epicenter) increased by nearly 94%. MMR vaccinations increased by 82% in the Upstate region and by 31% statewide.
  • As of April 24, the U.S. has reported 1,877 measles cases in 2026—an increase of 26 cases in the last week.
  • New evidence suggests that measles transmissionin the Arizona/Utah outbreak likely began more than six weeks before the first case was confirmed, with the true number of infections estimated to be at least 6.5 times higher than reported.
  • The Pan American Health Organization (PAHO) is urging countries in the Americas to intensify immunization efforts as part of Vaccination Week in the Americas (VWA), held from April 25 to May 2.
    • Measles has risen sharply throughout North and South America in 2025 and 2026—with the entire region losing its measles elimination status last November.
    • PAHO’s director Dr. Jarbas Barbosa described rising cases in the region as a “significant setback, but one that is entirely reversible.”

Respiratory Season Winding Down While Rotavirus Spread Continues

  • As of April 24, national respiratory illness activity remains at very low levels.
    • Flu activity continues to decline. All states are reporting low or minimal activity levels.
      • Six additional pediatric flu deaths were reported in the past week, bringing this season’s total to 149.
    • Unchanged from last week, Covid activity remains low, and hospitalizations continue to decrease.
    • RSV activity is elevated, but has peaked in most regions of the country.
  • Cases of rotavirus, a highly contagious infectious disease that affects the gastrointestinal system, remain slightly elevated. Rotavirus most often affects infants and young children, and commonly spreads from January to June in the U.S.
    • Public health experts explain that receiving the rotavirus vaccine, which reduces the risk of severe disease by 85-90%, is the best way to prevent its spread.

Respiratory Season Winding Down While Rotavirus Spread Continues; New Research Estimates Consequences of Changes to Hepatitis B Vaccine Recommendations

  • New research highlights the likely consequences if the federal hepatitis B birth dose recommendation were removed, projecting increases in infections, worse health outcomes, and millions of dollars in additional healthcare costs.
    • It finds that even modest reductions in birth dose coverage could lead to hundreds of additional infections over time, particularly among infants who are not identified as at-risk at birth.
    • While ACIP and CDC moved to halt the universal birth dose recommendation in late 2025, the CDC’s official childhood immunization recommendations have been reverted to include the hepatitis B birth dose amid ongoing litigation.
    • Hepatitis B vaccination at birth has been standard practice in the U.S. since 1991 and has dramatically reduced transmission in early childhood. This analysis underscores what’s at stake for public health if such recommendations were removed.

REALITY CHECK

These fact checks respond to several recent claims made by different groups and individuals.

CLAIM: mRNA vaccines aren’t effective against respiratory diseases, such as Covid and flu.

  • REALITY: Evidence consistently shows that mRNA vaccines are effective against respiratory diseases like Covid—particularly in preventing severe illness, hospitalization, and death, even if they do not always prevent infection.
    • Like many respiratory vaccines, mRNA Covid vaccines are not designed to fully block infection. Instead, their primary goal is to reduce the risk of serious outcomes—and real-world data show these vaccines provide protection across age groups.
  • In the U.S., there are licensed mRNA vaccines for Covid and RSV. Globally, there are also licensed mRNA combined Covid/flu vaccines.
  • Across multiple studies, Covid vaccination consistently demonstrates protection against severe outcomes and death.
    • A 2025 systematic review found moderate-to-high effectiveness against hospitalization across age groups during the 2025–2026 season.
    • A 2023 meta-analysis found unvaccinated individuals were nearly 2.5 times more likely to die from Covid.
    • Among hospitalized patients, those who had received two or three vaccine doses were 90–94% less likely to require ventilation or die, per CDC data.
    • Earlier data showed hospitalization rates were up to 17 times higher among unvaccinated individuals.
  • mRNA technology is also being applied to other respiratory diseases, with early evidence showing similar potential to reduce severe outcomes.
    • Data show that the FDA-approved mRNA RSV vaccine reduced the risk of RSV-related lower respiratory tract disease by up to 80% among older and high-risk adults.
    • A combined Covid/flu mRNA vaccine—recently approved in Europe—demonstrated stronger immune responses to both viruses compared to standard vaccines given separately in clinical trials.
  • On a population level, these effects translate into substantial public health impact—estimates suggest Covid vaccines prevented approximately 1.6 million hospitalizations and 235,000 deaths among U.S. adults between 2020 and 2021.
  • Taken together, the evidence shows that while mRNA vaccines may not fully prevent respiratory infections, they are highly effective at reducing the most serious and life-threatening outcomes.

CLAIM: The flu vaccine is only 20% effective and receiving it makes you more likely to get infected.

  • REALITY: How effective a flu vaccine is changes each year based on how well the vaccine matches circulating strains—in well-matched seasons, vaccines have shown up to 60% effectiveness in preventing infection that requires medical intervention. In less well-matched seasons, vaccination still provides meaningful protection by reducing the likelihood and severity of illness.
    • Because the influenza virus mutates frequently—and flu vaccines must be developed months in advance based on predictions about which strains will circulate—vaccine matching can fluctuate each season and flu vaccines are not always perfectly matched.
  • While flu vaccines do not always prevent infection, studies consistently show that vaccination reduces the risk of severe illness, complications, hospitalization, and death. For example:
    • Data from the 2022-2023 flu season in the U.S. show that vaccinated adults ages 18-64 were about 47% less likely to be hospitalized with flu compared to those who were not vaccinated.
    • Another study modeling the 2017-2018 respiratory illness season found that flu vaccines helped avert an estimated 7.1 million illnesses, 3.7 million medical visits, 109,000 hospitalizations, and 8,000 flu-related deaths in the U.S.
  • Additionally, beyond preventing infection, research shows flu vaccination also helps reduce serious complications and longer-term health risks.
  • Further, claims that vaccination makes infection more likely are not supported by credible, scientific evidence. Many years of investigation demonstrate that vaccinated individuals are less likely—not more—to get the flu.
    • According to a CDC analysis of pediatric flu deaths that occurred during the 2024-2025 season, 89% of deaths occurred in unvaccinated children. Another study found that flu vaccination, even in a season with a vaccine and circulating strain mismatch, was still protective in preventing severe influenza in children admitted to the intensive care unit.
  • Beyond the health impacts, a recent study found that the 2023-24 flu season cost the United States nearly $29 billion, and that increasing vaccination could have prevented tens of thousands of deaths and lowered healthcare costs.

WHAT TO WATCH

Pentagon Ends Longstanding Flu Vaccine Requirement for Service Members

  • Defense Secretary Pete Hegseth announced April 21 that U.S. military personnel will no longer be required to receive the annual flu vaccine, marking a significant shift in military immunization policy.
    • The announcement stated that service members will now be able to choose whether to receive the vaccine, framing the move as an effort to restore individual autonomy.
    • The flu vaccine had been required for decades—dating back to the mid-20th century—and was intended to protect force readiness, particularly in close-quarter settings. The U.S. military first instituted its vaccination program in 1777 under General George Washington.
  • Public health experts and some lawmakers have raised concerns that ending the requirement could lead to increased illness, missed duty time, and hospitalizations among troops, potentially impacting readiness.

Schrier Introduces VFC Legislation to Reinforce Pediatric Vaccine Access

  • Representative Dr. Kim Schrier (D-WA) introduced legislation aimed at strengthening the Vaccines for Children (VFC) program—which provides free vaccines to eligible children—amid growing concern about instability in federal vaccine policy and guidance.
  • The proposal focuses on improving patient access by expanding program eligibility to cover more children, combatting vaccine hesitancy, and tracking immunization to better understand and address existing gaps.
  • The effort comes as stakeholders raise alarms about maintaining consistent access to routine childhood immunizations, particularly for low-income and underinsured populations who rely on VFC.

HHS Leadership Flux Continues as Schwartz Nomination Signals Potential Stability

  • Leadership changes and restructuring across HHS, including CDC and advisory bodies, continue to reshape the federal public health landscape, contributing to broader uncertainty around policy direction.
  • Recent congressional hearings have amplified bipartisan concern about vaccine policy and the balance between political leadership and scientific agencies.
  • Against this backdrop, Dr. Erica Schwartz’s nomination for CDC Director is gaining support from key Republicans, including Cassidy, and is increasingly viewed as an opportunity to reinforce stability and credibility in public health leadership.

Kennedy Signals Potential Overhaul of USPSTF Membership Following Senate Scrutiny

  • Kennedy has indicated plans to appoint new members to the U.S. Preventive Services Task Force (USPSTF) after lawmakers raised concerns about disruptions to the panel’s work during last week’s Senate Finance Committee hearing.
  • A Federal Register notice published last Thursday (Apr. 23) calls for applications from specialists such as anesthesiologists, cardiologists, and oncologists—which experts say could undermine the panel’s broad focus. The panel has historically been comprised of primary care clinicians with expertise in preventive medicine.
  • The discussion follows reported pauses to USPSTF activities, including canceled meetings, which have heightened scrutiny of how preventive care recommendations are being managed.

Gavi Funding Remains Stalled as U.S. Role in Global Immunization Faces Uncertainty

  • U.S. funding for Gavi, the public-private Vaccine Alliance that helps provide vaccines to more than half of the world’s children, remains unresolved as appropriations leaders advocate to prevent rollbacks to prior commitments.
    • Kennedy claimed during Congressional hearings last week that he is not releasing the funding because Gavi uses a diphtheria, tetanus, and pertussis (DTP) vaccine that has largely been phased out in the U.S. Gavi stated that the vaccine “is safe and effective and estimated to have saved 40 million lives in the past 50 years.”
  • The U.S. has historically been one of Gavi’s largest donors, and prolonged delays are raising concerns about disruptions to routine immunization programs in low- and middle-income countries.
  • Health leaders warn that gaps in funding could slow progress on childhood vaccination coverage and increase the risk of outbreaks of vaccine-preventable diseases.

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