Possibility of Respiratory Syncytial Virus Resurrection in Canada

Key Point

  • In Australia, and more recently in the United States, cases of respiratory syncytial virus (RSV) infection have revived in parallel with a decline in pandemic-related physical distance measurements.

  • Canada needs to anticipate a similar resurgence and monitor respiratory illness so that it can respond quickly with strong RSV precautions.

  • In Canada, there have been few cases of RSV infection for months. This means that pregnant women and babies have low exposure and therefore children may have low levels of immunity.

  • A resurgence of cases in the summer of 2021 could expand resources in pediatric intensive care units across Canada.

  • The respiratory syncytial virus program should prepare the most at-risk infants for off-season immune prophylaxis.

In Australia, and more recently in the United States, cases of respiratory syncytial virus (RSV) infection have revived in the summer due to relaxed physical distance measurements associated with the COVID-19 pandemic. We argue that Canada should anticipate a similar resurgence of the seasonal respiratory virus in the summer of 2021. It is important to inform the RSV prevention program and continue to monitor respiratory illness to protect vulnerable patients. This may include giving RSV monoclonal antibody therapy to high-risk children during the off-season. This is a major departure from standard practice.

Prior to the COVID-19 pandemic, lower respiratory tract infections killed an estimated 2.7 million people worldwide annually, ranking fourth in mortality by cause.1 Respiratory syncytial virus and influenza are the leading causes of lower respiratory tract infections in young children. In children under 2 years of age, RSV manifests as bronchiolitis, and in younger babies, it presents with nonspecific symptoms such as apnea and decreased oral intake. There is no RSV vaccine and there is no population-level intervention other than basic hygiene measures. In Canada, high-risk children under the age of 2 including preterm infants and infants with severe chronic lung disease or severe congenital heart disease are currently RSV-neutralized monoclonals monthly during the RSV season (usually from late fall to early spring). I am receiving antibody therapy. Canada),2 This reduces the risk of hospitalization associated with lower respiratory tract infections by more than half. This occurs each year at a fixed date based on past epidemiology, or at the beginning of a fluctuating season based on active surveillance.

Since the beginning of the pandemic, it has been observed that cases of RSV and influenza have almost completely disappeared in many countries.3,Four In Canada, tests for RSV 339 627 were reported through the Center for Immunization and Respiratory Infections. Of these tests, 239 were positive between August 29, 2020 and May 8, 2021.Five By comparison, the RSV 412 861 test was reported during a similar period of the previous year (August 25, 2019 and May 2, 2020), of which 18860 were positive. In response to the apparent disappearance of RSV during a pandemic, several Canadian RSV programs have suspended, shortened, or even suspended seasonal administration of monoclonal antibodies to avoid unnecessary medical visits. ..6 However, a seasonal resurgence of RSV cases has recently been reported in the Southern Hemisphere with reduced SARS-CoV-2 circulation and relaxed physical distance measurements.7,8 The Centers for Disease Control and Prevention also issued a health warning on June 10, 2021 regarding the increase in seasonal RSV activity in the southern United States since March 2021 ( The out-of-season resurrection of the seasonal respiratory virus can pose a threat to vulnerable babies.

The resurgence of RSV cases in Australia and the United States highlights the importance of herd immunity in controlling RSV epidemics after peak exposure. Studies have reported cyclical fluctuations in maternal antibody levels that increase in winter and then decrease in summer.9 During the RSV season, most affected adults under the age of 65 remain asymptomatic or develop mild illness due to lifelong seasonal exposure to the virus and memory B and T cell immunity. .. In contrast, immunologically naive babies rely on maternal antibodies that are passively transferred to protect them at birth, but these antibodies declined within 6 months. Asymptomatic tests at home indicate that the infection may have continued to occur undetected during the COVID-19 pandemic.Ten However, during a pandemic, pregnant individuals are less likely to be exposed to RSV and are therefore less likely to boost RSV antibodies to levels normally seen in winter. This causes the baby to be less protected than usual and can become ill if infected this summer.

In Australia, during the recent reappearance of RSV, the median age of children who tested positive for RSV increased to 18.4 months. This was higher than the 2012-2019 cap (7.3-12.5 months). NS <0.001).7 This may suggest that infants who were not exposed to RSV in the first year did not develop sufficient immunity and thus remained susceptible until the second year. Australian pediatric intensivists said in the first four months of 2021 (late summer, early fall months after the blockade), older children (Trevor Duke, Royal Pediatrics) needing mechanical respiration. We reported an increase in severe atypical RSV cases in a children’s hospital (Melbourne). , Australia, personal communication). If a similar phenomenon occurs in Canada, pediatric intensive care unit (ICU) resources could expand at the expense of the disease in the summer of 2021. However, no public data was found on changes in public health responses to the off-season surge. In cases of RSV and influenza, we recognize that some Australian jurisdictions have decided to start monoclonal therapy early and prolong RSV immunoprevention until the case subsides.

In anticipation of the potential for RSV revival in Canada, we propose the following approaches. First, as the measurement of physical distance associated with pandemics has been relaxed, healthcare providers need to continue to emphasize basic hygiene measures such as washing hands. We support ongoing efforts to keep vulnerable babies out of contact with people with respiratory illness. Other protective measures, such as avoiding exposure to breastfeeding and indirect smoking, should be continued and emphasized where possible. Second, confirmatory RSV testing should be continued as usual to provide surveillance data. Third, as reported in Australia, pediatric ICUs need to predict an increase in severe RSV cases.7 The respiratory syncytial virus program should prepare the most at-risk infants for off-season immunoprevention if the case increases to a level that normally triggers the start of the fall season.

In Canada, the RSV program has not yet positively defined how many cases of RSV infection constitute recurrence, but even a small number of cases are of interest, especially given the fact that 0 cases were seen weekly for several months. It makes sense to think that you need to trigger communication with stakeholders. In many jurisdictions. Nevertheless, it is worth mentioning that it is unclear whether the use of off-season RSV monoclonal therapy is cost-effective in this context. Although drug shortages are not expected, new arrangements may need to be adjusted earlier than usual for the shipment and storage of palivizumab in case of RSV recurrence. Finally, to document the pandemic effects on the cyclical outbreak of seasonal viruses and to understand why RSV and influenza disappeared over the past year while SARS-CoV-2 and rhinovirus continued to circulate. Research is needed.11


The author would like to thank Dr. Manish Sadarangani, David Goldfarb, and Joan Robinson for their ongoing and insightful discussion on this issue and for the expert opinion on this commentary.


  • Competing profits: Pascal Lavoie and Alfonso Solimano are members of the executive committee, and Alfonso Solimano is a publicly funded program under the State Health Services Department of the British Columbia Department of Health for the British Columbia Respiratory Syncytroid Virus (RSV) Immunoprevention Program. I am a medical director. Joanne Langley’s research site uses GSK, Janssen, and Pfizer to conduct research on RSV vaccines. Funding for these studies will be paid to Dalhousie University. No other competing interests were declared.

  • This article has been peer reviewed.

  • Contributor: All authors contribute to the conception and design of the work, draft the manuscript, critically revise it for important intellectual content, give final approval of the published version, and take responsibility for all aspects of the work. I agreed to bear.

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Possibility of Respiratory Syncytial Virus Resurrection in Canada

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