Explained: What is Twindemic and what is its impact on India?
The ongoing COVID-19 pandemic paired with flu season presents the threat of a dangerous combination of infectious diseases or twindemic and may strain hospitals in the coming months.
A team of researchers who have expertise in mathematical modeling and vaccination policy of infectious disease said that the war against the COVID-19 pandemic is not yet over and new threats are awaiting. These mathematical models have often predicted cases, hospitalizations and death.
Their recent researches suggest that last year’s shrink in the influenza season may lead to a rise in flu cases in the coming season. The experts are urging people to get their shot of flu along with COVID-19.
How anti-COVID measures may lead to a surge in flu?
Ever since the very first case of COVID-19 was reported from China’s Wuhan, travel restrictions, social distancing, closer of offices and institutions, along with hand hygiene and masks were put in place to contain the spread of the deadly virus.
The above anti-COVID measures tamped down influenza and other infectious diseases during the last flu season but will hit harder this year. This is due to the fact that the natural immunity that people develop when they are exposed to the infected population has dropped due to travel restrictions, social distancing and other restrictions.
What is influenza and what are the risks involved?
Influenza is caused by multiple strains of the RNA virus that mutates at various type of rates every year to form new strains of the virus. Therefore, immunity to influenza involves several factors. These are:
1- Similarity of the strain to the one that the child was first exposed to.
2- Whether circulating strains are similar to previous strains or not.
3- Timeline of influenza infections-- how recent the infections were if they occurred.
4- Mass gatherings, protective measures such as using masks and hand hygiene, all affect the transmission of viruses between people.
6- Population immunity from vaccination depends on the proportion of people who get the flu vaccine in a given season against the circulating influenza strains.
Given that the 2020-2021 flu season has had one of the lowest recorded numbers of cases in US history, a large epidemic of flu combined with deadly COVID-19 pandemic could be witnessed this year. However, no historical examples can be quoted of dual or simultaneous epidemics.
Models used to predict twindemic
The team of researchers used two different models to forecast the potential impact from last year’s shrink in influenza cases to that of this year. The yet to be peer-reviewed research predicted a spike in flu cases in the coming season.
One of the modeling systems simulated an actual population’s interactions at home and work and in school and neighbourhood settings. The model predicted a huge rise in the number of cases this flu season.
The other model was a traditional infectious disease modeling tool that divides the population into groups of people who are-- susceptible to infection, infected, recovered, hospitalized and died. Based on this model, it is predicted that the number of hospitalization surpasses the number of cases that typically occur during the flu season.
The possibility of a twindemic is expected to overburden the already stressed healthcare system due to the ongoing COVID-19 pandemic. Also, infants and young children are at greater risk as they have not been exposed to the previous seasons of influenza and thus have not developed immunity in comparison to the adult population. Influenza in children affects grandparents and other elderly people.
As there is variability in vaccination rates, social distancing norms and mask-wearing, a substantial variation in flu cases across India will be witnessed same as the patterns of the COVID-19 pandemic. Also, vaccination against influenza and COVID-19 is important to contain the dramatic increase in cases and to keep hospitals in India from becoming overwhelmed.