Doctors warn cases of respiratory virus could surge as pandemic precautions reduced

A premature baby is pictured in the neonatal intensive care unit of Mount Sinai Hospital in Toronto in this file photo taken, Sept. 11, 2013. THE CANADIAN PRESS/Galit Rodan

As social distancing and travel restrictions relax amid declining COVID-19 infection rates, doctors are cautioning about a potential off-season resurgence of respiratory syncytial virus (RSV), which tends to affect infants and older adults.

RSV is a leading cause of lower respiratory tract infections such as pneumonia and bronchitis, which in a typical year lead to around 2.7 million deaths globally, according to a commentary published on Monday in the Canadian Medical Association Journal. It is very common and contagious, and presents as bronchiolitis in young children under the age of two.

“We wanted to alert mainly the medical community, the need to be prepared … and also for families, particularly for parents of high-risk babies,” said Dr. Pascal Lavoie of the BC Children’s Hospital Research Institute and the University of British Columbia, one of four co-authors of the commentary, in an interview.

According to the Lavoie and his colleagues, cases of RSV dropped sharply during the pandemic, as social distancing measures all but stopped its spread. In Canada, for instance, only 239 tests for RSV were positive between Aug. 29, 2020 and May 8, 2021, compared to 18,660 positive tests during the same period a year earlier.

However, easing COVID restrictions has caused case numbers to start rising in both Australia and the United States, and Canada should expect the same, the doctors said.

“We argue that Canada should anticipate a similar resurgence in seasonal respiratory viruses in the summer of 2021,” the authors wrote.

While the majority of RSV cases involve no symptoms or just a mild illness, children born prematurely or with chronic lung or congenital heart disease are at higher risk.

“Most babies are okay with this virus, but there are a few who have very high risk….The advice we would give them in the winter would be to stay away from other people that have colds. So I think they need to be a bit more careful over the summer because nobody’s used to seeing RSV coming right in the middle of summer,” said Lavoie.

There is currently no vaccine for RSV, but adults younger than 65 tend to be protected from serious illness due to immunity build up from seasonal virus exposure, while pregnant women typically pass on short-term immunity to infants.

But according to the commentary, the lack of cases during the past year meant most pregnant women and very young infants were not able to develop immunity. This in turn puts young children potentially at risk for more severe illness this year.

“The off-season resurgence in seasonal respiratory viruses now potentially poses a threat to vulnerable infants,” wrote the authors.

Additionally, higher-risk children such as those with chronic lung or congenital heart disease are typically treated with a monthly antibody therapy, which significantly reduces the risk of hospitalization. However, many antibody programs were paused or suspended in the past year in part due to the lack of RSV cases and to reduce unnecessary medical visits during the pandemic.

With typically few to no cases in the summer, Lavoie noted, many antibody treatments are seasonal as well.

“We need to make sure that we’re prepared -- so stocking doses and having nursing staff and everything in place in case cases go up again,” said Lavoie.

In order to stave off a potential rise in cases, the authors are also suggesting that Canadians continue to emphasize handwashing and basic hygiene measures, as well as other potentially protective measures such as breastfeeding, which passes on antibodies to children, avoiding second-hand smoke, contact with those who are sick, and staying home if sick themselves.

They also recommend continued testing for RSV when required, as well as planning by pediatric intensive care units to managed a potential increase in RSV cases. They also suggest administering preventative treatment to the highest-risk infants during the summer if cases begin to return to normal levels.

There are already a few cases in Eastern Canada, Lavoie said, so immunity will gradually build up particularly in infants, but doctors want to buffer some of the rise in cases. Lavoie says they have data they hope to have peer reviewed and published that show a “significant loss of RSV immunity in the population.” This is “not a big deal” in adults, but something to watch for in infants, particularly those that have complex medical conditions, he explained.

“This letter was not meant to be alarmist,” said Lavoie. “But I’m a neonatologist, so I see babies that are quite vulnerable and I want to make sure that there’s awareness and that those who are really high risk are protected.”