MEDICALLY REVIEWED

Pfizer RSV Vaccine Protects Infants and Older Adults in Clinical Trials

Pfizer’s respiratory syncytial virus (RSV) vaccine has shown promising results in protecting infants and older adults from the illness caused by this virus, according to two company-funded trials.

If approved by the Food and Drug Administration (FDA), these vaccines could be the world’s first approved RSV vaccines.

What is RSV?

RSV is a highly contagious virus that is widespread and can affect people of any age. 

In most cases, it causes a mild infection with the following symptoms: 

  • Coughing
  • Sneezing
  • Fever 
  • A decreased appetite. 

In infants under six months and older adults, RSV can be severe and even deadly.

Protecting Infants Through Vaccination of Pregnant Women

In one trial, Pfizer’s RSV vaccine was given to pregnant women during late-stage pregnancy, with the aim of protecting infants from birth through six months of age. The vaccine was effective against severe RSV-associated lower respiratory tract illness such as pneumonia and bronchiolitis. 

The vaccine was 82% effective during the first 90 days of life and 69% effective over the first six months of life.

According to Dr. Coleen Cunningham, professor and chair of paediatrics at the University of California, Irvine, this decline in effectiveness is expected because antibody levels in the infant diminish over time. However, vaccinating pregnant women is expected to be very helpful during the first several months of life, which is a time when infants are most vulnerable.

Researchers did not identify any safety concerns in infants or women who received the vaccine. Pfizer has asked the FDA to approve its RSV vaccine for pregnant people to protect infants, and the company expects a decision by August 2023.

Protecting Older Adults Through Vaccination

In another trial, the Pfizer RSV vaccine was 67% to 86% effective in adults 60 and older against RSV-associated lower respiratory tract illness such as acute bronchitis and pneumonia. The vaccine was also 62% effective against RSV-associated acute respiratory illness.

Researchers did not identify any safety concerns in this age group, and the rates of adverse events were similar in vaccine recipients and the inactive placebo group. Three serious adverse events identified in vaccine recipients were thought to be related to the vaccine, but the FDA and the Centers for Disease Control and Prevention will continue to monitor their safety if approved.

Protecting Children Through Vaccination

Dr. David Diemert, a professor of medicine and microbiology, immunology and tropical medicine at George Washington University School of Medicine & Health Sciences, said Pfizer’s RSV vaccine is a very important development, particularly for protecting young children. Vaccinating pregnant women is a proven and safe way of getting high levels of antibodies to babies that will protect them against invading viruses and other disease-causing organisms.

The George Washington University Vaccine Research Unit is about to start recruiting 18- to 60-year-olds for a phase 3 clinical trial of Pfizer’s vaccine. This trial will focus on adults in this age group who are at higher risk of developing severe disease due to the RSV virus because of coexisting medical conditions such as asthma, diabetes, or chronic kidney disease.

RSV: A Serious Threat

The virus is a significant threat, causing up to 80,000 hospitalizations and up to 300 deaths each year among children younger than age five in the United States, according to the National Foundation for Infectious Diseases. RSV also causes up to 160,000 hospitalizations and up to 10,000 deaths in adults age 65 years and older.

There is currently no specific treatment for RSV infection. Treatment involves managing symptoms and providing supportive care. However, the availability of safe and effective vaccines for RSV could significantly reduce the number of hospitalizations and deaths caused by this virus.

Impact on Public Health

If approved, the Pfizer vaccine could have a significant impact on public health, particularly for infants and older adults who are at high risk of severe illness or death from RSV. Vaccinating pregnant women with the RSV vaccine could provide passive immunity to infants during the first several months of life, protecting them from severe RSV illness.

Similarly, vaccinating older adults with the RSV vaccine could reduce the incidence of severe RSV-associated lower respiratory tract illness, such as acute bronchitis and pneumonia. This could reduce the burden on healthcare systems, which are already stretched thin due to the COVID-19 pandemic.

Looking Ahead

The Pfizer RSV vaccine has shown promising results in clinical trials, but further research is needed to confirm its safety and effectiveness in larger populations. The FDA and other regulatory bodies will continue to closely monitor the safety of these vaccines if approved.

In addition to the Pfizer RSV vaccine, other vaccine candidates, such as those from GlaxoSmithKline and AstraZeneca, are also being reviewed by the FDA for approval. These vaccine candidates could provide additional options for protecting against RSV.

Overall, the development of effective vaccines for RSV is a significant step forward in protecting vulnerable populations from severe illness and death caused by this virus. As research continues, the hope is that these vaccines will become widely available and accessible, helping to reduce the burden of RSV on public health systems around the world.

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