Public Health Note: Infectious Respiratory Disease Winter 2023/24
Temporal disclaimer: This information is accurate as of the date of publication and may be superseded as the situation evolves.
Infectious respiratory diseases include Covid, colds, and flu. After the global Covid pandemic starting in 2019 there has been a concern that increases in an infectious respiratory disease indicate that another pandemic is starting. Although there have recently been increases in the incidence of pneumonia in China, the current evidence suggests that a pandemic is unlikely.
Why are infections respiratory diseases a concern?
There are people who could become seriously ill following a respiratory infection, such as people who are immunocompromised or people over 65. However, there is growing evidence that for most people in the UK, Covid is becoming a seasonal inconvenience, like colds and flu, and is no longer as dangerous as it once was.
Although we should not take these diseases lightly and we must protect the vulnerable, we are not expecting cases to overload our healthcare system as much as in 2020/21.
Causes of pneumoniaMultiple things can cause a person to develop pneumonia. It generally clears up by itself, although some people may need antibiotics/antivirals/antifungals, depending on what caused the pneumonia. Some people who get bad cases of pneumonia can become severely ill and may need hospitalisation. Young children, people with compromised immune systems, and people with pre-existing respiratory issues are most at risk of this.
Preventing the spread of infectious respiratory viruses
We should be treating all respiratory infections as things to avoid spreading to other people, whatever disease they are. Professor Tildesley of Warwick University, who was heavily involved in infection modelling during the pandemic, is quoted in a BBC article saying ‘If there is one thing we have learnt from the pandemic, it is the importance of trying to stay away from people if you are ill with a respiratory virus. That is as true for flu and other respiratory viruses as it is for Covid.’. Right now, whether you have Covid or not is less important than the question of whether or not you feel ill enough that you shouldn’t be around people.
It's hard to know how long a person is infectious for once they have become ill. It’s difficult to study, and probably differs a lot from person to person. ‘Viral load’ is the amount of virus detectable in a person’s blood, saliva, or other samples, which broadly correlates with their infectiousness. During the pandemic, we saw that viral load varied a lot between people and didn’t always relate to how ill they felt. A small study of infectiousness in people with Covid suggested the average infectious period after symptom onset is five days. Some people will with Covid will be infectious for longer, others for less.
We should avoid making one another ill. We need to leave behind the mindset that it is admirable to ‘soldier on’ and come to work when you feel unwell, only to infect other people. People who are eligible for Covid and flu vaccinations should continue to get them. We should all continue to practise good hand, cough, and sneeze hygiene. If you believe you are ill, it’s considerate of people around you to avoid unventilated spaces or, if you like, to wear a mask inside them. Long Covid is still something to try and avoid. The condition is still poorly understood and hard to treat, and as far as we understand it, remains a potential outcome from anyone with a Covid infection, although the risk does appear to be falling.
If the UK has truly learned our lesson from the pandemic, we will be ready and prepared for some restrictions to be put in place. This could be necessary due to Covid, flu, or a new infection at any time, but particularly in winter months.
What is the current situation in the UK?In 2022 in the UK, there were several Covid waves across the year, but 2023 data suggest a more seasonal pattern, driven by people spending more time indoors in poorly ventilated spaces in winter. This also drives the rise in other infectious diseases at this time . The repeated exposures during 2022, and the success of the vaccination programme, appear to have given us good protection against severe disease from currently circulating variants. Among people who do get Covid, fewer are subsequently developing the long-term symptoms called ‘long Covid’.
What is the current situation in China?
Cases of pneumonia among children in China are unusually high as winter season begins this year. This is causing international concern that a new disease with pandemic potential is circulating. So far, there is no publicly available evidence that this is the case. The rise in cases is being described as an epidemic in some sources, which means more cases of the condition than the country would normally expect, across several regions. The WHO has made an official request for more detailed information.
The cases in China are being described as ‘walking pneumonia’ and ‘white lung syndrome’. The term ‘pneumonia’ itself means inflammation of the lung tissues. ‘Walking pneumonia’ describes a mild form of the condition where the person is still able to walk around and do normal things, but feels under the weather and may have a cough or difficulty doing strenuous things. ‘White lung’ describes how the condition looks on lung X-rays , where this inflammation is visible as white spots.
China is entering its first winter without restrictions in place to prevent the spread of Covid-19. The country has had longer and stricter lockdowns than many other countries. China has also relied on a domestically developed vaccine which is less effective than the ones being used elsewhere. This means that the population there has had less exposure to Covid-19, are not as protected by their vaccine, and are therefore more likely to become seriously ill if they contract it. The lockdowns have also prevented other common respiratory viruses spreading, so immunity to those is lower. This particularly impacts children, who are normally exposed to many different diseases in their first few years of life at nursery or school, which would contribute to their immune system development. In the last few years, children in China have not had that normal exposure. A sudden rise in infections among a population with lower immunity could explain the rise in pneumonia.
Adults are not becoming ill at the same rate that children are, which lends further strength to the theory that lack of exposure to common diseases is the epidemic’s cause . Moreover, China has reported no unusual or novel pathogens among these pneumonia cases. The evidence suggests that the pneumonia cases have occurred in people who became ill due to a variety of common and expected pathogens.
We need more information about why the current pneumonia in China has slightly different symptoms to recent outbreaks, and a better understanding of what diseases it is associated with to understand whether it poses a threat to people in other countries. So far there is no evidence that the disease in China poses a pandemic threat to the rest of the world.
Is the current situation in China a cause for concern?
This winter, there are more cases of pneumonia being reported in China than in previous years. This is leading some to worry that a new and potentially serious disease is circulating there which could spread and disrupt global health systems.
Some sources are calling the pneumonia in China ‘mysterious’, ‘undiagnosed’, or of ‘unknown origin’. This language sounds concerning, but means that either cases were found in the community which had been mistaken for colds or flu, or there were no specific tests done to identify the exact pathogen responsible. This is often the case, because tests are not required for treatment. Most tested cases appear to have been caused by the most common pneumonia pathogen – Mycoplasma pneumoniae bacteria. This normally causes walking pneumonia in most people, but in this outbreak appears to have caused hospitalisation in an unusually large proportion of cases.
We need to know why the current pneumonia in China has slightly different symptoms to recent outbreaks. We also need to know what diseases it is associated with to understand whether it poses a threat to people in other countries. So far there is no evidence that the disease in China poses a pandemic threat to the rest of the world.
Protection against infectious respiratory disease in the UK
To ensure you and your loved ones have the best possible protection from infectious respiratory diseases, consult your general practitioner about what vaccines you are eligible for, and make sure you’re up to date.
The NHS website guidance about pneumonia states that:
Pneumonia can be more serious in people who are over 65, people with cardiovascular or lung conditions, young babies, and children. These people are more likely to need to go to hospital if they contract pneumonia.
Symptoms of pneumonia, which can start suddenly or gradually and last for 2-4 weeks, are:
- a cough – you may cough up yellow or green mucus (phlegm)
- shortness of breath
- a high temperature
- chest pain
- an aching body
- feeling very tired
- loss of appetite
- making wheezing noises when you breathe – babies may also make grunting noises
- feeling confused – this is common in older people
Ask for an urgent GP appointment or get help from NHS 111 if:
You should call 999 if you are:
- you have had a cough for three weeks or more
- you’re coughing up blood, you have chest pain
- you’re feeling short of breath.
- struggling to breathe
- have pale blue or blotchy skin, lips or tongue
- if you feel suddenly confused
- if you cannot wake your baby and they feel floppy.
The webpage also describes treatments you may receive if you have pneumonia, what you should and should not do if you have pneumonia, the causes of pneumonia, and the people for whom a pneumonia vaccination is recommended.
Undiagnosed pneumonia - China: (BJ, LN) children, reported epidemic, RFI, ProMed, International Society for Infectious Diseases 21/11/23
WHO statement on reported clusters of respiratory illness in children in northern China, World Health Organisation, 2023