SSI: Denmark Also Reporting A Summer Surge In RSV

 

#16,062

One of the dramatic side effects of the COVID pandemic - and our collective social distancing response to it - has been the huge reduction in other infectious diseases around the world.  

The wearing of  face masks, social distancing, and increased hand washing has driven many other respiratory viruses to ground, to the point where collecting influenza samples for making this year's vaccine has been difficult. 

The wavy line of red triangles at the bottom of the FluView Graphic above show the unprecedented low level of ILI - or Influenza-like Illness (including flu, Rhinovirus, RSV, Adenovirus, etc.) reported to the CDC over the past 12 months.

As we've discussed often over the past year (see here, here, here, and here), this lack of exposure to common respiratory viruses - whether due to social distancing,  NPIs (face masks, hand hygiene,etc.) or `viral interference' from COVID - is a double-edged sword.

• In the short run, it makes it easier to identify COVID cases, lessens the burden on healthcare delivery systems, and avoids the enhanced risks due to dual infections.

• But at the same time, this lack of exposure allows our community immunity to these viruses to wane over time, potentially setting us up for serious epidemics when they finally do return. 

A month ago, in CDC HAN: Increased RSV Reports Across The Southern United States, we looked at an unusual off-season surge in Respiratory Syncytial Virus across parts of the US after more than a year without appreciable non-COVID respiratory illness (see chart below)

While last week, in ESCMID: When Respiratory VIruses Return & New Zealand's RSV Resurgence, we looked at another outbreak of RSV in the Southern Hemisphere. 

Today, we have a brief report from Denmark's SSI (Statens Serum Institut), on an unusual summer surge of RSV there, as well. 

So far, 112 cases of RS virus have been found in weeks 20-26. 

On a normal summer, one would only see about a handful of cases.

Last edited July 12, 2021

Everything has been turned upside down due to the covid-19 epidemic. This is also true of the RS virus, which is usually only seen in winter, where it is the most common cause of acute bronchitis. However, that was not the case this winter. On the other hand, according to the Statens Serum Institut (SSI), 112 RS cases have so far been found this summer in week 20-26.

“On a normal summer, you would typically find about a handful of cases. The high number we see now is therefore very unusual ", says section manager Ramona Trebien from SSI.
Due to the restrictions

During the covid-19 epidemic, several of the common respiratory infections did not occur. This includes the flu and RS virus.

It is therefore expected that the few RS cases this winter will be an effect of the many restrictions and hygiene measures that have been put in place against covid-19.

Conversely, it is estimated that the increasing number of RS cases we are seeing now is due to the restrictions being softened or completely removed. The same pattern has been seen in countries such as the USA and Australia ", says Ramona Trebien.

Doctors need to pay attention

Due to the unusually high number of cases, SSI advises doctors to also think of RS virus when they have patients with respiratory infections.

RS virus rarely hits adults particularly hard. In turn, the RS virus is the most common cause of acute bronchitis in young children in winter. It can also develop into pneumonia.

Facts about RS virus

• RS virus is an abbreviation for respiratory syncytial virus.
• During the winter months, RS virus is the most common cause of acute bronchitis in young children.
• RS virus typically affects children under two years of age - most often children under six months.
• Adults of all ages can also be affected, but they are rarely severely affected.
• Children under six months are often hospitalized if they get the RS virus. This is especially true if the child has difficulty breathing and has difficulty eating, drinking and sleeping.

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As countries decide to loosen their social contact restrictions - as is occurring across much of the United States and in the UK - the risks for seeing new epidemics of RSV, measles, influenza, and other (primarily) respiratory viruses goes up. 

Not only can this make the diagnosing, and isolation, of COVID cases more difficult, there are studies suggesting that coinfection of influenza and COVID may produce more severe illness and less favorable outcomes (see PHE Study: Co-Infection With COVID-19 & Seasonal Influenza).

Another good reason why I'll continue to wear face masks in public for the foreseeable future.