After six decades of research marked setback after setback, scientists have scored a major win against RSV (respiratory syncytial virus): On March 31, the US Food and Drug Administration (FDA) approved a vaccine from Pfizer aimed at preventing potentially serious complications from RSV. In adults age 60 and over.
The approval of the RSV vaccine, called Abrysvo, comes less than a month after the FDA gave the green light to the world’s first RSV vaccine, Arexvy, from GlaxoSmithKline (GSK).
“A vaccine to help prevent RSV has been an elusive public health goal for more than half a century,” Annaliesa Anderson, PhD, senior vice president and chief scientific officer for vaccine research and development at Pfizer, said in a statement. “Abrysvo will address the need to help protect older adults from the potentially serious consequences of RSV disease.”
Together, the new RSV vaccines represent a major advance in protecting the elderly against this highly contagious virus. The elderly are particularly vulnerable to severe illness caused by respiratory syncytial virus, as are infants and immunocompromised persons.
The Centers for Disease Control and Prevention (CDC) estimate that RSV leads to 60,000 to 160,000 hospitalizations annually among adults age 65 and older. About 6,000 to 10,000 older adults die each year from RSV-related lower respiratory tract disease.
“These large numbers may seem surprising to some because we often don’t hear much about RSV in older adults,” says Beth Thielen, MD, PhD, assistant professor at the University of Minnesota College of Medicine in Minneapolis. “Because there are no specific treatments for RSV in the elderly, health care providers are often discouraged from transmitting [them for] RSV test, so it almost certainly goes undiagnosed.”
The Pfizer vaccine was very effective in the studies
The Pfizer syringe has been shown to be more than 85% effective in late-stage trials against severe illness caused by RSV, and approximately 67% effective in preventing lower respiratory illness overall.
These research findings were based on data from more than 37,000 adults ages 60 and older.
The GSK and Pfizer vaccines work on a similar principle. Both trigger a highly protective response to RSV by targeting a part of the virus, called a pre-fusion F protein, that allows it to attach to and infect human cells.
“The vaccine causes the body to make antibodies that stick to the F protein on the surface of the virus,” says Dr. Thieln. “This F protein is necessary to allow the virus to enter the cells to infect them, so if there is an antibody attached to this protein, it does not allow the virus to enter the cells.”
There are two main types of RSV (A and B). They both run during the same season, but overall, one prevails. Unlike the GSK vaccine, Pfizer’s product is a bivalent product that contains ingredients that specifically target strains A and B of RSV.
Unlike the Pfizer vaccine, the GSK shot contains an adjuvant, which is a drug designed to make the vaccine more effective.
The Pfizer and GSK vaccines have proven to be highly effective against RSV strains, with minimal side effects (mainly pain at the injection site, swelling, and fatigue).
“There were a few cases of a heart condition called atrial fibrillation and a neurological condition called Guillain-Barre syndrome in study participants who received the vaccines,” Thelin says. “These were rare events, and further study in a larger population will be needed to determine if this is really related to the vaccines.”
A common virus can cause serious problems
RSV is a common respiratory virus that usually produces mild, cold-like symptoms, which pass within a week or two. Typical symptoms are runny nose, decreased appetite, coughing, sneezing, fever, and wheezing.
Most people can beat the illness at home by getting plenty of rest and fluids, and taking over-the-counter fever reducers, such as acetaminophen or ibuprofen.
In the elderly and other vulnerable populations, the physical effects of the virus can be severe and even life-threatening. Some patients need intensive care if they develop bronchiolitis (inflammation of the small airways, or bronchi, in the lungs) or pneumonia (inflammation of the lungs).
The virus is spreading so widely that everyone has been infected by their second birthday, according to the Centers for Disease Control and Prevention (CDC). People can contract the virus repeatedly during their lifetime.
“We know that people can get reinfected many times,” says Thieln. “Immunity diminishes in the elderly, so we see more serious diseases in them and in weakened immunity.”
If patients have significant difficulty breathing or become dehydrated, they may need to be admitted to hospital to receive supplemental oxygen, intravenous fluids, or in the worst circumstances intubation (a breathing tube inserted through the mouth and into the airway) using mechanical ventilation (a machine that assists person to breathe). In most cases, hospitalization lasts only a few days.
How much will the new RSV vaccines cost?
Pfizer and GSK both expect the shots to cost nothing or little for most seniors.
“The recently enacted Reducing Inflation Act will greatly help eliminate barriers to access because it allows for $0 payments for vaccines needed for adults under Medicaid and Medicare Part D,” says Keanna Ghazvini, a Pfizer spokeswoman.
An RSV shot to protect infants may be next
While the recent FDA approvals are good news for older adults, there is currently no RSV vaccine for infants. But Pfizer hopes the FDA will approve the RSV vaccine as a maternal immunization, which means pregnant women will get the vaccine and pass protective antibodies on to their babies in the womb.
A decision from the Food and Drug Administration on this use is expected in August.