This week in JAMA Network Open, a team led by researchers from respiratory syncytial virus (RSV) vaccine-maker Pfizer reported an elevated risk of cardiorespiratory events in adults for up to six months after RSV hospitalization.

For the self-controlled case series (SCCS), the investigators obtained data on 11,887 patients from the Optum Market Clarity Dataset on US RSV hospitalizations and related outcomes from January 2017 through March 2024. 

The aim was to compare the incidence of cardiorespiratory events during the risk period (the six months after RSV hospitalization index date) and control periods (more than 21 days before or 180 days after the index date).

Participants had at least one RSV hospital admission and one or more cardiorespiratory events (heart attack, stroke, chronic obstructive pulmonary disease [COPD] exacerbation, congestive heart failure [CHF] exacerbation, and abnormal heart rhythms). The average age was 69.4 years, and 61.4% of participants were women.

Pfizer makes the RSV vaccine Abrysvo, which is approved for older adults, younger adults at high risk for severe disease, and pregnant women to protect their infants.

“RSV has been clinically underrecognized as a cause of severe respiratory illness among adults for several reasons, including nonspecific symptoms, infrequent standard-of-care testing rates, narrow case definitions that exclude some RSV disease (eg, influenza-like illness), and low sensitivity due to lower viral loads than in children and the use of single-specimen polymerase chain reaction testing,” the study authors wrote.

Arrhythmia most common heart-related event

The most common cardiorespiratory event was arrhythmia (5,844 patients), followed by COPD exacerbation (5,018), CHF exacerbation (4,204), heart attack (2,421), and stroke (1,622). In the first 14 days after RSV hospitalization, risk was elevated for each cardiorespiratory event, with the highest estimated incidence rate ratios (IRRs) occurring in the initial seven days. IRRs compare the speed of health outcome occurrence between two groups.

For heart attack, the IRRs were 8.7 from days 1 to 7, falling to 5.2 for days 8 to 14 and 2.6 on days 15 to 21. For stroke, the IRRs were 7.4, 5.9, and 3.7, respectively, with a comparable pattern for CHF exacerbation (12.5, 4.1, and 2.4, respectively). For COPD exacerbation and arrhythmia, the IRRs dropped during the first three weeks, from 23.1 through day 7, to 1.3 on days 15 to 21, and from 16.5 to 1.6, respectively.

IRR estimates were significantly elevated for all outcomes except COPD exacerbation for as long as 42 days and attenuated with time. The risk stayed significantly elevated after RSV hospitalization for up to 63 days for heart attack (IRR, 1.8) and stroke (IRR, 1.8) and up to 84 days for CHF exacerbation (IRR, 1.5).

Potential role in triggering heart/lung complications

“Our findings are similar to those of other SCCS studies assessing the association between influenza or COVID-19 and cardiorespiratory events, especially in the first 7 days following the infection,” the investigators wrote. 

Results of our study support a potential role of RSV infection in triggering cardiorespiratory complications in adults, especially older adults, and present a clinical and economic burden beyond the acute phase of the illness.

They said that respiratory illnesses such as influenza and SARS-CoV-2 have been tied to cardiovascular events such as heart failure and acute coronary syndrome, as well as pulmonary embolism and deep-vein thrombosis. But the link between RSV and cardiorespiratory disease isn’t as well-established as those for flu or COVID-19.

“Results of our study support a potential role of RSV infection in triggering cardiorespiratory complications in adults, especially older adults, and present a clinical and economic burden beyond the acute phase of the illness,”the authors wrote.

The findings highlight the need to increase RSV vaccination in adults, they said, noting that the Centers for Disease Control and Prevention (CDC) recommends RSV vaccination for adults aged 60 to 74 years at increased risk for severe illness (ie, those with chronic cardiovascular or respiratory disease) and all people 75 years and older. 

The team also called for research to further delineate the pathogenesis of RSV and its role in asthma, COPD, and cardiovascular disease.