Nepal has been witnessing a significant rise ininfluenza cases over the last few weeks. In fact, influenza has resurfaced in Nepal since the start ofthe year 2021. The second wave of the coronavirus is not yet over in Nepal, meaning influenza and the coronavirus are simultaneously circulating in the country, or there is a "twindemic".

The term "twindemic" refers to the dual threat of a severe influenza outbreak on top of the COVID-19 pandemic.

A couple of days ago, a 32-year-oldwoman visited the fever clinic of the Sukraraj Tropical and Infectious Disease Hospital (STIDH) with a history of chest congestion, throat pain, fever, headache and cough. She felt stress, anxiety and fear after having symptoms similar to those of COV- ID-19. She, however,tested negative for SARS-CoV- 2that causes COVID-19.

The author advised the patient to go for an influenza virus test, which ultimately showed a positive result (influenza B).

In another instance, a family visited the STIDH with intense fear of COV- ID-19 after all household members developed fever, cough and sore throat.

They, however, tested negative thrice for SARS- CoV-2. They also eventually tested positive for the influenza virus.

These are just a few examples of a situation of co-circulation of influenza virus and coronavirus in Nepal. Interestingly, the author has seen some people infected with both the viruses.

Many scientists believe that it is more likely that with both viruses infecting the same person at the same time, the severity of the respiratory illness will be greater.

British researchers have found that the risk of death more than doubled for people who tested positive for both the influenza virus and coronavirus, compared to the coronavirus alone. Nevertheless, so far, the author has not observed more severe symptoms of respiratory illness in these dually-infected people, although a high level of vigilance should be maintained in the coming days in order to understand the disease outcome or clinical conditions.

Each year, Nepal observes two seasons of influenza virus –firstly during January-March, and secondly in the months of July-August.

To my surprise, however, last year, there were almost no flu activity in Nepal as well as in other parts of the world. In fact, last year, scientists had expected to see double trouble of coronavirus and influenza viruses during the flu season, dubbed the "twindemic".

In Nepal, the influenza virus has made a comeback since the start of the year 2021. Over the past few weeks, Nepal has been witnessing influenza virus infection almost double in number at approximately two-week intervals. Influenza type A and type B are being detected in Nepal.

At present, H3 virus that belongs to type A influenza, popularly known as Hong Kong flu, is widely circulating in Nepal. Interestingly, H1N1pdm09 virus, which belongs to type A influenza and also known as swine flu, has not been detected so far. Swine flu (H1N- 1pdm09) and Hong Kong flu (H3) have been simultaneously circulating during the influenza seasons in Nepal.

Type B influenza virus has increased significantly in the last two weeks. It is divided into two lineages known as "Yamagata" and "Victoria". Until now, almost all influenza B viruses found in Nepal belong to the "Victoria" lineage. A few type B influenza viruses are neither of "Victoria" nor "Yamagata" lineages, meaning a new lineage of type B influenza virus might be emerging in Nepal.

Further studies, however, are warranted to identify the new virus and its possible impact on vaccine effectiveness.

The difference between COVID-19 and influenza viruses cannot be made solely based on clinical symptoms. Nowadays, people believe that every cough or fever is a symptom of COVID-19, which is causing mental or psychological disorders. As a result, individuals who develop flu-like symptoms tend to fear death due to COV- ID-19 complications because very recently Nepal has experienced the deadliest second wave of the coronavirus, which was by far the worst and quite unexpected or unpredictable.

The polymerase chain reaction (PCR) technology is useful in differentiating between the flu and COV- ID-19. An accurate detection of viruses is essential for appropriate counselling and treatment. PCR technology is now available in all provinces of Nepal.

Last year, influenza virus had almost disappeared, preventing a potential twindemic situation worldwide.

The delta variant of the coronavirus that resulted in a deadly second wave is still circulating in Nepal, while influenza virus has also been increasing dramatically for the last couple of weeks. It seems that the delta variant and influenza virus can co-circulate simultaneously at a given place and time period, creating a twindemic situation.

According to the Indian news media, in Delhi, 41 percent of the respondents reported at least one member of their household currently has flu-like symptoms.

In other words, influenza virus is widespread in Delhi city, and perhaps even spreading to other parts of the country.

It is worthwhile mentioning that the delta variant was first detected in India that led to a deadly second wave of the coronavirus.

Delta has now become the dominant variant in the US and the UK. It is, thus, highly likely that a twindemic may occur during the upcoming influenza season.

To sum up, Nepal is perhaps among the few countries where a twindemic challenge is being faced. At present, it is not clear if a twindemic situation can create a worse situation than COVID-19alone. Nevertheless, it is clear that fear, anxiety and panic are much higher amongst those who display flu-like symptoms, and health care workers have difficulty distinguishing between the two viruses. Such conditions may occur in countries where the influenza season is fast approaching.

Dr Pun is Chief, Clinical Research Unit, Sukraraj Tropical and Infectious Disease Hospital

Type B influenza virus has increased significantly in the last two weeks. Until now, almost all influenza B viruses found in Nepal belong to the "Victoria" lineage, not the "Yamagata" one. A few type B influenza viruses are neither of "Victoria" nor "Yamagata" lineages, meaning a new lineage of type B influenza virus might be emerging in Nepal

A version of this article appears in the print on August 24 2021, of The Himalayan Times.