Social distancing and other measures put in place due to the coronavirus pandemic will trigger a spike in flu cases next winter, a study warns.
So-called non-pharmaceutical interventions – behavioural changes which curb the spread of disease – have been in force for much of 2020. They include wearing face masks and social distancing.
These measures have not only helped to break the chain of transmission for Covid-19, but have also slashed infection rates of other diseases.
As a result, seasonal influenza and respiratory syncytial virus (RSV) have infected a fifth fewer people in the United States in 2020 than in an average year, data shows, a.
However, researchers caution that this apparent bonus will have a knock-on impact in the coming years, because it increases the pool of susceptible people.
The number of at-risk individuals will likely increase further, as masks and social distancing are expected to remain in place for several months due to the Covid-19 pandemic.
They will likely only be scrapped after a vaccine has been widely rolled out and proven to be effective.
When this happens, potentially in the Spring of 2021, other viruses will seize on the abandonment of these measures, infecting the now bloated susceptible population.
As respiratory disease and viruses always thrive in the coldest months, researchers expect the winter of 2021-2022 to be beleaguered with flu and RSV cases.
Princeton University scientists warn it is likely these future outbreaks will ‘increase the burden’ on healthcare systems.
Flu data for Hawaii shows that when non-pharmaceutical interventions came into force in March (vertical dotted line) the number of flu cases (blue line) fell far below the previous years (grey dots). This will lead to a flu spike in winter next year, experts predict
The vertical dotted line shows when the COVID-19 pandemic broke out and masks and social distancing started. The dots are previous data for flue levels in previous years. For Minnesota, the actual cases for 2020 (blue line) is far below normal rates. This will create a larger susceptible population going forward
While some diseases spread more easily than others, some are more dangerous, with a higher mortality rate, and some are very difficult to create a vaccine for.
Seasonal flu, for instance, changes rapidly via mutations and as a result a vaccine is only partially effective, meaning a different one must be made every year.
But flu’s mortality rate is less than 0.1 per cent, whereas the coronavirus is around three per cent, making flu far less deadly.
This is the main reason Covid-19 has been so rampant in society – it spreads slightly slower than the flu but is more likely to kill the people it infects.
Flu also benefits from an element of herd immunity, where many people in a population are protected from reinfection because they have, at a previous point, caught the virus and fought it off.
Therefor, they have developed their own protection and antibodies can fight off an infection.
The annual flu vaccine is given to vulnerable people whose immune systems may struggle to do this, such as the elderly and pregnant.
These graphs show the forecasts for RSV cases in Texas and Florida going forward. The blue dotted line represents the number of people who are susceptible. It spikes after the grey shaded area, which is the period of time where masks and social distancing are likely to be enforced. The red line shows the previous (pre-2020) or future amount of people infected with RSV. It is expected to soar in the winter of next year due to the larger susceptible population. In Florida it could be four times the norm, and in Texas it could be twice the norm
Scientists have released the most up-to-date illustration of the coronavirus ever made(pictured), mapping both its external appearance and internal structure
Pfizer’s Covid-19 vaccine is ‘90% effective’
One of the leading coronavirus vaccine candidates has proven to be 90 per cent effective, marking a major breakthrough in the global race to stop the disease.
Pfizer and BioNTech today said that early results from a massive clinical trial suggest nine out of 10 people who get their jab are protected from coronavirus by it.
In an update on progress in the ongoing study, the pharmaceutical companies said that of 94 people infected with the virus so far, at least 86 of them had been in the placebo group.
The placebo group is one in which people are given a fake vaccine so that what happens to them can be compared with those who get the real thing. Pfizer’s trial has split the participants half and half across the placebo and vaccine groups.
The company’s chairman hailed the breakthrough a ‘great day for science’ while independent experts said the results are ‘excellent’ and ‘really impressive’.
RSV is another virus which affects the respiratory system and is passed from one person to the next.
It is extremely common and most children have been infected before the age of two.
However, it can also infect adults and older children, with its symptoms manifesting in a similar way to the common cold.
RSV can cause severe infection in some people, especially premature babies, older adults, infants and adults with heart and lung disease, or anyone with a very weak immune system (immunocompromised).
Researchers from Princeton University used data from this year on infection rates with seasonal flu and RSV and compared it to the level of previous years.
Since masks, social distancing and travel bans came into force in the US, there has been a drop of 20 per cent in RSV transmission.
As a result of people being less infected now, more people are susceptible going forward.
‘We find that substantial outbreaks of RSV may occur in future years, with peak outbreaks likely occurring in the winter of 2021–2022,’ the researchers write.
‘Results for influenza broadly echo this picture, but are more uncertain; future outbreaks are likely dependent on the transmissibility and evolutionary dynamics of circulating strains.’
The full findings are published in PNAS.