What cold season means for Covid-19


Now that the cold season is here, will there be more coronavirus infections?

It is almost that time of the year, again, when cases of the flu and common cold increase. June marks the onset of the cold season in which many people battle with respiratory tract infections.

Although flu cases are present in Kenya throughout the year, research shows infections tend to be highest during cold and wet weather - from February to April and June to November.

“While annual epidemics coinciding with the rainy season have been observed in many (sub) tropical locations, biannual incidence is the norm in some regions, and influenza activity occurs throughout the year in others,” states a research report published by PubMed Central.

June and July are very cold months in Kenya and the onset of short rains from October to December also witnesses a surge in flu cases. The flu spreads on a worldwide scale and cases are increasing in Africa due to the rains, which started in March, and cold weather.

The question in many people’s minds now is whether this cold season will deepen the coronavirus crisis the world currently faces. Kenya has more than 450 Covid-19 cases already. Could the flu season result in more cases?


With the Centers for Disease Control and Prevention (CDC) having warned that there could be a second wave of the novel coronavirus that is likely to be more catastrophic than the first, Kenyans are advised to be cautiously optimistic about the possibility of saying goodbye to the deadly virus.

CDC says should the second wave of Covid-19 coincide with the start of the flu season, there could be more trouble.

So far, not much is known about Sars-Cov-2, the Covid-19 causing virus and research on its seasonality is still underway. However, experts say if it behaves like other coronaviruses, then the cold weather may trigger more cases.

According to research, coronaviruses are usually associated with cold weather, especially because of the way they are spread. Infected droplets spread better when the air is cold and dry. The spread is lower during humid, warm weather because the droplets fall to the ground faster, making transmission harder.

Since this is not the first time the world is finding itself in the grip of a coronavirus outbreak, experts agree there could be pointers as to what to expect of this new virus. One of the three most dangerous coronaviruses is Sars coronavirus (Sars-Cov), which broke out between 2002 and 2004.

A study published published in the Journal Advances in Virology in 2011 on the behavioural characteristics of Sars-Cov established that the virus survived best in cooler, drier conditions.

Research shows cold weather generally worsens upper respiratory tract infections. Therefore, experts argue, if the lethal Sars-Cov-2 virus is like Sars-Cov, the flu or common cold – which are also caused by viruses - then Kenyans should prepare themselves for one of the worst seasons of upper respiratory tract infections.

“We have experience and evidence of increased illnesses and deaths from respiratory tract infections during the cold season,” says Dr Benard Muia, a public health expert and chairman of the Murang’a Health, Water, Sanitation and Environment Services.

He says cold weather may be counter-productive in the alleviation and prevention of the spread of Covid-19. “Covid-19 is a respiratory tract infection (RTI) and with this weather, there is a likelihood of more illness and deaths from RTIs if measures to control the spread are not undertaken broadly,” said the former Nairobi Health executive.


Dr Muia says the disease is yet to peak despite the government relaxing some directives. “The peak is expected to be in seven to 12 weeks from now. It is going to coincide with June and July when it is very cold,” he adds.

This is the same period when cases of cold and the flu are expected to increase.

A research published by the Centre for Evidence-Based Medicine, but which has not peer-reviewed, shows that cool and dry conditions seem to favour the spread of Covid-19.

"Temperature positively correlates with the rate of infection spread, whereas it negatively correlates with humidity. Every one degree Celsius increase in the minimum temperature, leads to a decrease in the cumulative number of cases by 0.86,” shows the research carried out in 429 cities, mainly in China.

If nothing is done to avert a flu outbreak that coincides with Covid-19 infections, the result could be disastrous because the two are hard to tell apart as their symptoms are mostly similar.

“Many people have poor health-seeking behaviour and may spread it thinking that it is common cold,” says Dr Muia. “To know the difference between the flu and Covid-19 or any other respiratory tract infection, a victim should do a diagnostic test.”

According to the World Health Organization, the two are common in many ways. “They both cause respiratory diseases, which present as a wide range of illnesses from asymptomatic or mild through to severe disease and death,” says WHO.

One of the shared symptoms is coughing and sneezing, which are triggered by either cold weather or drastic weather change. Transmission of both diseases is through droplets from an infected person. This means if there are more people sneezing and coughing, the risk of transmission is higher.


For an already bulging health system dealing with rising cases of coronavirus infections, a flu outbreak is likely to cause more harm. Already, healthcare systems have been prioritising Covid-19 patients. A rise in flu cases amid Covid-19 outbreak is likely to overwhelm the health system. Costs are high and equipment scarce. The cost of treating a Covid-19 patient is Sh1 million, according to the Health ministry.

Expansion of health facilities is ongoing to cater for the increasing number of Covid-19 patients. Kenyatta National Hospital, for example, launched the Mbagathi wing, which is used for isolating Covid-19 patients. This is happening in most counties, with Makueni County having converted a youth centre to a Covid-19 facility while Murang’a County has constructed an intensive care unit for the same patients.

To combat the virus, recruitment of an additional 6,000 medical and health workers is underway. All these amid a strike threat by healthcare workers who have complained about “lack of safety” while dealing with coronavirus patients.

During a recent interview with the Washington Post, CDC director Robert Redfield cautioned that the flu epidemic occurring simultaneously with Covid-19 pandemic will mean critically overwhelmed healthcare providers and health systems. Data on Covid-19 suggests that while 80 per cent of infections are mild or asymptomatic, 15 per cent are severe infection requiring oxygen and five per cent are critical and in need of ventilators.

According to Dr Muia, people tend to stay indoors when it is cold making it impossible to observe the physical distance needed to keep Covid-19 at bay. In addition, this environment – poorly ventilated - will be very suitable for the transmission of Covid-19.


Amesh Adalja, a physician and a scholar at the Johns Hopkins Center for Health Security in a report published by National Public Radio argues that Covid-19 seems more akin to the seasonal cold. Up to a third of common colds are caused by coronaviruses.

"We've seen, basically, explosive spread inside China of person-to-person transmission, so — in that sense — it really is behaving like a common cold causing coronavirus," he says.

According to him, seasonality plays a role in the spread of Covid-19, which means that the cases could increase in Kenya and other African countries, which are getting colder and decrease in Europe, which is getting warmer.

However, Dr Mark Nanyingi, an infectious disease epidemiologist at the Institute of Global Health and Infection, University of Liverpool, thinks it is too early to make conclusions. He says the novel coronavirus has violated the weather assumption and may not behave like the flu or cold. “People confuse Covid-19 with the flu. The novel coronavirus is an influenza-like illness, but not the flu,” says Dr Nanyingi.

It has only been four months into the pandemic and it is not possible as at now to say what the trend will be, he argues. “We are yet to establish if it will disappear like Sars. We may not understand it until it sticks around for a while,” says Dr Nanyingi, who is also a lecturer at the School of Public Health at the University of Nairobi. He, however, does not rule out the possibility of the Covid-19 virus following a pattern similar to that of the flu. He agrees that cold weather increases coinfections.

What he sees as a looming threat to efforts to combat Covid-19 is the displacement thousands of people by floods as a result of heavy rains. Currently, at least 30,000 people have been displaced, according to the Kenya Red Cross Society.

These people are exposed to cold weather conditions and subsequent illnesses, which include the flu and common cold. “It is unfortunate that the pandemic is happening in these climatic conditions, which predispose people to lung infections,” he says.

Dr Nanyingi calls upon the government to ensure the safety of those displaced to protect them from diseases, saying it is impractical to practise social distancing in such circumstances.

The epidemiologist reiterates that there is a potential second wave of Covid-19 in the region, and which might be more explosive compared to the first one. He says seasonal temperatures may not matter as much in the spread because transmission is dependent on human behaviour.


His assertion that weather might have little to do with the coronavirus disease are supported by Mr James Kaoga, a lecturer at the University of Nairobi Institute for Climate Change and Adaptation.

According to him, if warm weather would stop the spread, then there would be minimal cases of Covid-19 in Mombasa, which is warm.

Dr Ian Njeru, an epidemiologist, agrees. “We do not have information about seasonality of Covid-19. People can only speculate,” says the former Head of Disease Surveillance and Response at the Health ministry.

He, however, says if Covid-19 will be assumed to behave like flu, then we may expect increased cases during the cold season.

Dr Jeremiah Chakaya, a respiratory physician allied to the Respiratory Society of Kenya, says although it is too early to make any inferences about weather and Covid-19 at this point, flu makes people sick and kills thousands of people during winter.

“But we do not have the same degree of difficulty because we usually have influenza throughout the year and it does not come as an epidemic. We may get lucky in the tropics, but it is still very early,” he says.

Usually, when people suspect they have a common cold or the flu, pharmacies are the first place they turn to. This in turn means demand for flu and cold medication will be higher. To avoid a crisis, Dr Nanyingi says pharmaceutical companies must scale up development of drugs to address the flu and to manage Covid-19 symptoms. “So much is unknown about this virus, with potential mutations, many drugs may become ineffective quickly,” he says.

Although it is too late for a Covid-19 vaccine to help ease the burden in the current flu season, if one is found, then the next flu seasons will find stronger, well prepared health systems.

Despite there being evidence that antivirals like Remdesivir are promising efficacy, he says, there is need for further studies.

Dr Dominic Karanja from the Pharmaceutical Society of Kenya says Covid-19 has helped identify the gaps, challenges and opportunities. “We should use this opportunity to strengthen local research and manufacturing. We have the ability to produce medicine and medical equipment locally. We only need support to improve our capacity. Covid-19 is a wakeup call,” he says.