Flu in the context of COVID-19
6 December 2021 | Questions and answersWe spoke to Dr Richard Pebody, who leads the High-threat Pathogen team and the Surveillance and Laboratory pillar of the COVID-19 Incident Support Management Team (IMST) at WHO/Europe, to find out what danger influenza (flu) poses this year, what people can do to stay healthy, and what implications a possible “twindemic” of flu and COVID-19 could have for people, authorities and health systems.
Flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat and sometimes lungs. It can cause mild to severe illness and, for some people with underlying conditions, can unfortunately lead to death. In a normal year, around 70 000 people die from flu in the WHO European Region.
With international travel resuming and many societies opening up again, there is more potential for the flu virus to be introduced and to spread than last year. As flu rates were so low in 2020/2021, people might be more susceptible to the virus this year. This is particularly concerning as we go into the winter months, with more people mixing indoors and travelling, adding to the risk of catching and spreading the virus.
We’re also still in the midst of the COVID-19 pandemic, with the highly transmissible Delta variant in circulation, which could lead to a potential “twindemic” of influenza and COVID-19 this winter. Having both viruses co-circulating could have severe consequences for vulnerable people and place increased pressure on health systems at a time of year when hospitals are often at their busiest anyway.
Both viruses are highly infectious respiratory diseases and share many of the same symptoms, such as coughing, fever, shortness of breath, and/or loss of taste and smell. Because of the difficulty in distinguishing the diseases from symptoms alone, if you are symptomatic you should isolate yourself from other people to reduce the risk of the infection spreading, particularly to vulnerable people, and get tested for COVID-19 as soon as possible. While both diseases can cause serious illness, COVID-19 is more likely to lead to health complications, admission to hospital and, in some cases, death – so getting tested is essential.
WHO recommends that people from the following 5 priority groups get vaccinated before the flu season starts, or as soon as possible thereafter. This is usually around October to November, after vaccines become available.
- Health-care workers. As health-care workers are more exposed to flu through their work, their chances of passing the infection on to others, including vulnerable patients at risk of severe disease, are increased. We also rely on these workers to run our health services, so we need them to stay healthy at work, not be off sick with the flu, particularly at a time of year when health services are often under the most pressure.
- Older people over 65 years. As the immune system weakens with age, our bodies become less effective at fighting infections, including flu. This means older people have a greater risk of developing serious illness, may need hospitalization and could even die from the disease.
- People with underlying conditions, such as diabetes, lung disease or heart disease. Weakened immune systems can increase the risk of severe illness, hospitalization and potentially death from flu.
- Pregnant women. Evidence shows that pregnant women are more prone to developing severe flu, which can have a negative impact on the unborn child. Vaccination protects the pregnant woman, the fetus and the baby once born.
- Children under 5 years. Young children are more likely to develop more severe illness, and have the potential to infect others, including older relatives.
Each year, countries plan to order sufficient numbers of vaccines to cover their eligible populations. While it’s true to say that there is a fine balance between supply and demand, it’s important that health-care workers and those in vulnerable groups are prioritized in vaccination programmes.
There are 2 major human influenza virus types, influenza A and influenza B, which lead to annual flu epidemics (often referred to as the flu season). In Europe, we use both trivalent vaccines (to protect against 3 influenza strains) and quadrivalent vaccines (to protect against 4 strains) that cover both of these virus types.
Flu vaccines have been around for over 60 years and been safely given to millions of people around the world. Every year, national medicines regulatory authorities carefully examine each flu vaccine before it is licensed, and systems are in place to monitor and investigate reports of adverse effects following immunization. Although there are occasionally side effects, these are very rare and not normally severe. The flu vaccine is the best tool we have for preventing the disease and reducing the risk of serious complications and even death.
In order to provide an optimum level of protection, flu vaccines are updated annually based on the observations of scientists monitoring virus strains in circulation earlier that year. Exactly how effective these vaccines are depends on a number of factors, including your age, current health and the strains of the virus that actually end up in circulation over the winter period. Even so, we would typically expect you be around 60% protected from flu after 2 weeks of having been vaccinated (this is the usual time it takes for the vaccine to take effect).
No, the viruses are different and therefore require different vaccines.
Although evidence on getting COVID-19 and influenza vaccines at the same time (known as co-administration) is limited, what evidence there is does not show any increase in adverse effects. Therefore, WHO thinks it is acceptable for countries to give both vaccines to their citizens during the same visit, particularly as the risks of adults getting serious illness from flu or COVID-19 infection is substantial.
It is better to wait until you are given the all-clear from COVID-19 before getting a flu vaccine to avoid the possibility of wrongly attributing any symptoms to the vaccine.
As yet, we don’t have sufficient data to be able to say for sure whether having COVID-19 makes you more vulnerable to flu. After the virus emerged early last year, countries in the Region went into lockdown in March, so we saw very little circulation of the flu virus through the year, making it difficult to make any firm judgement on the effects of coinfection.
However, having said that, if someone was to be hospitalized because of COVID-19 and developed lung damage, then this would certainly increase their risk of severe disease if they were then to catch flu.
Both COVID-19 and flu are respiratory viruses and can be caught in the same ways – mainly through breathing in particles from an infected person when they cough, sneeze, speak or breathe, or when they pick up the viruses from contaminated surfaces. This means that the same measures for protecting yourself from COVID-19 apply to flu too:
- wash your hands regularly
- wear a mask when appropriate
- keep a safe distance from others – our recommendation is at least 1 metre
- avoid the 3Cs: closed, confined or crowded spaces
- ensure indoor spaces are well ventilated
- cough or sneeze into a tissue or your arm to avoid spreading the disease
- get vaccinated against both viruses if you’re eligible and when it’s your turn.
WHO/Europe carries out routine surveillance to understand the influenza virus situation in the Region, monitoring when it arrives, who it is affecting, how it is spreading and which strains are in circulation. Once the genetic make-up of these strains is understood, we share this information with laboratories across the Region and make recommendations on the most effective flu vaccines, co-ordinating with manufacturers to ensure they are updated as and when the situation changes. We also advise countries on the best ways to get a high level of vaccination uptake among their priority population groups.
The goal of the Flu Awareness Campaign is to increase uptake of flu vaccination among both health-care workers and at-risk population groups, to minimize the risk of sickness and death, and to reduce the impacts of flu on health-care systems and economies.
This will be achieved by supporting Member States to build acceptance and uptake of the flu vaccine among these groups as both an individual and a collective protection measure, particularly while we also have COVID-19 in circulation.