Q&A: Influenza in the context of COVID-19
12 October 2022 | Q&ADr Richard Pebody leads the High-threat Pathogen team and the Surveillance and Laboratory pillar of the COVID-19 Incident Support Management Team (IMST) at WHO/Europe. WHO/Europe is warning that cases of influenza and COVID-19 are likely to rise this autumn and winter season. We spoke to Dr Pebody to find out what we can do to prepare and how we can protect ourselves and those around us – particularly those who are vulnerable – and what threat a possible resurgence of influenza, alongside COVID-19, could have for countries and their people, and health systems.
Influenza is a contagious respiratory illness caused by the influenza virus that infects the nose, throat and sometimes lungs. For most people, it causes a mild but unpleasant illness; however, for some, it can lead to severe illness, hospitalization and death. This is particularly true for groups such as the elderly and those with underlying conditions or chronic diseases. Before the COVID-19 pandemic, globally we would see normally around 3–5 million people suffering from severe influenza and up to 650 000 people dying from the disease in a year. Around 70 000 of those deaths would be seen in the WHO European Region.
Although we have not seen significant transmission from influenza during much of the pandemic, the disease has not gone away. Late last season, we saw an increase in influenza – and we may see an early and significant increase in the transmission of influenza and other respiratory viruses this autumn and winter.
In brief, yes. At WHO/Europe, we are concerned about a resurgence of influenza this autumn and winter – alongside COVID-19.
While influenza and other respiratory viruses have circulated at lower levels in the Region over the last 2 years, we may well see an increase in the transmission of these viruses this autumn and winter. Countries need to be ready for this scenario, given what we have seen during the southern hemisphere's winter, where high levels of influenza were reported early in the season between May–June 2022, and the early atypical circulation of respiratory syncytial virus (RSV) – another respiratory virus – that was seen in Europe last year.
And with COVID-19 social protection measures easing and international travel increasing this year, there is more potential for the influenza virus to be introduced and to spread. Also, with influenza and other respiratory viruses having circulated at lower levels in the Region during much of the COVID-19 pandemic, more people might be susceptible to these viruses this year. This is particularly concerning as we go into the autumn and winter period, with more people mixing indoors, adding to the risk of catching and spreading infection.
And let’s not forget: We are not done with COVID-19 yet. WHO/Europe highlights the likelihood of a rise in COVID-19 cases and hospitalizations, alongside influenza, during the autumn and winter months.
This could present a huge challenge to the Region's health workforce, already under enormous pressure from dealing with the pandemic since early 2020; the health care system; and vulnerable groups across the Region. Many people at most risk of serious illness or death from influenza are also at most risk of severe or life-threatening COVID-19.
Both viruses are highly infectious respiratory diseases and share many of the same symptoms, such as coughing, fever and shortness of breath.
Because of the difficulty in distinguishing the diseases from symptoms alone, if you are symptomatic you should isolate yourself from others 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, particularly in those who are unvaccinated and/or previously uninfected, is more likely to lead to health complications, admission to hospital and, in some cases, death, compared to influenza – so getting tested is essential.
WHO recommends that people from the following 4 priority groups get vaccinated against influenza.
- Health care workers. Because health care workers are exposed to influenza through their work, they should be protected from becoming infected and spreading influenza. Immunization reduces the risk that they spread influenza to their patients, who are likely to be more vulnerable and at risk of severe disease. Health care workers are vital to the COVID-19 response, and as such, they need to be healthy at work, not off sick with the influenza.
- Older people over 65 years. The immune system weakens with age and becomes less effective at fighting infections, including influenza. People over 65 years who are infected with influenza are therefore at greater risk of experiencing severe outcomes, including hospitalization and death.
- Pregnant women. Pregnant women are more prone to severe influenza, and this can have a negative impact on the unborn child. Vaccination protects both the pregnant woman and baby once born.
- People with comorbidities and underlying conditions. Influenza can be very serious for people with comorbidities and underlying conditions, such as diabetes, asthma or heart disease. An influenza infection may worsen these conditions and result in hospitalization and potentially death.
Depending on national contexts, including capacity, resources, policies and priorities, a country may also want to target the following groups in their vaccination campaigns.
- Children under 5 years. They are at greater risk of experiencing severe disease or complications, such as hospitalization and, more rarely, death. Immunization also prevents children from infecting others, including grandparents and other vulnerable groups.
- People living in high-density accommodation settings, such as prisons, refugee camps and group homes (such as care homes). Immunization can curb the rapid spread of influenza in large group settings.
It’s important to note that many people at most risk of serious illness or death due to influenza are also at most risk of severe or life-threatening COVID-19.
WHO recommends that vulnerable populations – identified as the 4 priority groups – protect themselves from serious illness or death by getting fully vaccinated against both influenza and COVID-19 this autumn and winter.
It is best to get vaccinated before the influenza season starts. Influenza vaccination campaigns usually take place around October–November, soon after the vaccine becomes available. It takes 2 weeks from receiving a vaccine until protective antibodies against influenza have developed.
It is never too late to get vaccinated if influenza is still circulating; vaccination increases the chances of being protected from infection and may lessen severe consequences from the disease.
There are 2 major human influenza virus types – influenza A and influenza B – which lead to annual influenza 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.
The influenza vaccine is the best tool we have for preventing the disease and reducing the risk of serious complications and even death. Influenza vaccines have been around for over 60 years and have been safely given to millions of people around the world.
Every year, national medicines regulatory authorities carefully examine each influenza 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.
In order to provide an optimum level of protection, influenza 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 to be around 60% protected from influenza after 2 weeks of having been vaccinated, which is the usual time it takes for the vaccine to take effect.
The most common way that influenza vaccines are made uses an egg-based manufacturing process. This process has been used for more than 70 years. The egg-based process produces both an inactivated (killed virus) vaccine, which is the most common version that is given as an injection, and a live attenuated (weakened virus) vaccine, which is a nasal spray, used mainly in paediatric vaccination programmes.
“Enhanced” vaccines are adjuvanted, high-dose and cell-based. They are all licensed, and some show improved effectiveness in some seasons – though they are more expensive. Ultimately, their use depends upon health economics.
No, the influenza vaccine cannot give you influenza
No, the viruses are different and therefore require different vaccines.
WHO recommends that countries administer influenza vaccine along with COVID-19 vaccine – so-called coadministration – whenever feasible.
This will help increase uptake of both vaccines in priority groups, improve the efficiency of vaccine administration, and protect already stretched health care systems – given that the known risk of serious illness for older adults and other priority groups infected either with influenza virus or COVID -19 is substantial.
It is better to wait until you are given the all-clear from COVID-19 before getting an influenza vaccine to avoid the possibility of wrongly attributing any symptoms to the vaccine.
As yet, we do not have sufficient data to be able to say for sure whether having COVID-19 makes you more vulnerable to influenza. Since the onset of the pandemic, we have seen lower levels of influenza virus circulation due to the social restrictions put in place to curb COVID-19. It has been difficult to make any firm judgement on the effects of coinfection.
However, 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 caught influenza afterwards.
Influenza vaccines have been safely given to millions of people for decades.
In a few circumstances, however, seasonal influenza vaccine is not recommended or should be administered with extra care.
Getting seasonal influenza vaccine is not indicated for people who have had a severe allergic reaction after a previous dose or to a vaccine component. People with known egg allergies may be given egg-based influenza vaccine provided they are observed for at least 15 minutes afterwards in a setting where appropriate medical care is available.
It’s important that we keep up with safety precautions to protect vulnerable groups. Both COVID-19 and influenza 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 the viruses are picked up from contaminated surfaces. This means that the same measures for protecting yourself from COVID-19 will help to reduce risk of influenza infection for both yourself and vulnerable persons, including:
- wearing well-fitted masks, particularly indoors and on public transportation with crowded, closed and close-contact settings, or when visiting care home or health care facilities, for example;
- ensuring good ventilation of indoor spaces (particularly crowded and public spaces);
- cleaning hands regularly; and
- covering sneezes and coughs with a tissue or bent elbow.
As we have seen, these measures can work.
On 12 October 2022, WHO/Europe is launching its 10th annual Flu Awareness Campaign.
The 2022–2023 campaign aims to increase the uptake of influenza vaccination – as well as COVID-19 vaccination – amongst at-risk population groups in the Region to convey the importance of people continuing to take protective measures.
The campaign is part of WHO/Europe’s autumn/winter strategy for COVID-19 and other respiratory viruses – to help countries and individuals prepare for an expected rise in infections.
WHO works on influenza all year round. When one season finishes, preparedness work begins for the next. This work includes: surveillance and tracking the influenza virus, monitoring the different strains that laboratories find; making the recommendations for the composition of the vaccine each year; surveillance of avian influenza, known as bird flu, which can cause human infection; and tracking mortality from influenza and the burden of disease.
Whether it’s COVID-19 or influenza, vaccination is the best tool we have for preventing disease and reducing the risk of serious complications and even death.
COVID-19 vaccine roll-out continues to progress in most countries, including in lower- and middle-income countries. Yet, millions remain unvaccinated in many parts of WHO/Europe’s region; we must find better ways to reach them. While doing so, we need to prioritize giving booster shots to the most vulnerable, including older adults, immunocompromised individuals and those with underlying medical conditions.
Overall, the consistent application of these 5 interventions may be useful in protecting populations from COVID-19, but also influenza, by:
- increasing vaccine uptake in the general population;
- administering additional vaccine doses to priority groups;
- promoting mask-wearing indoors and on public transportation;
- ventilating crowded and public spaces, such as schools, bars and restaurants, open space offices and public transportation; and
- ensuring optimal clinical management for cases at risk of severe disease.
WHO/Europe’s autumn/winter strategy for COVID-19 and other respiratory viruses can help countries better prepare for responding to a likely increase of COVID-19 and influenza.