The non-pharmacological measures adopted in 2020 and 2021 to combat Covid19 have had their effect in reducing the spread of Sars-CoV2 but not only, in fact between 2020 and 2021 seasonal flu has practically disappeared.
Covid, influenza and respiratory syncytial virus
Influenza is a disease caused by a respiratory virus not very different from Sars-CoV2 so it should not surprise us that the non-pharmacological measures (masks, spacing, lockdown etc.) adopted to counter the spread of a virus also impact on circulation of the other.
Influenza and syncytial virus: in the laboratory, the two viruses merge and deceive the immune system
by Irma D’Aria
The flu is not the only virus to have been perturbed by the anti Covid19 measures, in fact lately there is also a lot of talk about RSV respiratory syncytial virus.
Respiratory syncytial virus mainly affects children under the age of 5, and in some categories it is very dangerous and is the second leading cause of death for children.
Immunity to the RSV virus is short-lived and it is not uncommon for a child to become infected several times in the first years of life: in adults, on the other hand, it occurs rarely or with very mild symptoms. Children in the 2020-21 period had fewer social interactions, in some cases they wore masks, while today contacts have returned to pre-pandemic levels and therefore the incidence of RSV is rising again.
Children who did not contract RSV in 2020-21 are contracting it now, which explains the increased incidence of the disease around the world.
Children without mask risk new outbreaks of respiratory syncytial virus
by Alessandra Volpe
So was the children’s immune system weakened by the 2020-21 no exposure?
Our adaptive immune system (T lymphocytes and antibodies) works with repeated stimulation, basically every time our immune system encounters an antigen it will build a more robust and hopefully specific immune response. This operation is exploited by vaccines which through various boosters present a viral antigen to the immune system so that it can train itself to fight that specific pathogen.
The fact that the immune system works by repeated stimulations, however, does not in any way justify wanting to voluntarily infect oneself. Every time we come into contact with a pathogen we run a risk that we cannot know in advance, viruses have evolved to enter our organism and reproduce without control.
The only real training for our immune system is the vaccine that presents the viral antigen in a controlled and safe way.
The recent increase in RSV cases can therefore be explained from an epidemiological rather than an immunological point of view: children who did not contract the disease in 2020-21 contract it now but their immune systems are not weakened by the lack of exposure.
Syncytial virus, 1-2 year old children remain defenseless
TAKE HOME MESSAGE:
- Non-pharmacological measures adopted during the Covid19 pandemic impacted the circulation of Sars-CoV2 and other viruses
- RSV is a respiratory virus that primarily affects children and can be dangerous in some categories, reinfections with RSV are common in the first few years of life.
- In recent months, many children have contracted RSV because they were not infected during 2020-212
- the immune system does not need to be trained with repeated infections that always pose a risk to those who contract them
REF:
https://www.scientificamerican.com/article/flu-has-disappeared-worldwide-during-the-covid-pandemic1/
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(22)00525-4/fulltext
https://www.ncbi.nlm.nih.gov/books/NBK27090/