Why do COVID-19 cases begin to increase as winter approaches? Let’s delve into the explanation provided by an expert

Why COVID-19 Cases Start To Rise With Winter Onset: Expert Explains

Why COVID-19 Cases Start To Rise With Winter Onset: Expert Explains

Amidst the escalating numbers of respiratory illness cases attributed to COVID-19 and its newly identified sub-variant JN.1, the World Health Organization (WHO) is urging Southeast Asian nations, including India, to heighten surveillance efforts and implement precautionary measures.

Globally, there has been a 52% surge in new COVID cases, with reports of the new sub-variant JN.1 emerging in various countries such as the United States, China, and Singapore.

In India, the active cases have surpassed the 4,000 mark, with a total of 116 new cases of COVID-19 reported. Among these, 63 cases of JN.1 have been identified, with the highest number reported in Goa (34), followed by Maharashtra (9), Karnataka (8), Kerala (6), Tamil Nadu (4), and Telangana (2), according to the Health Ministry.

The recent spike in COVID cases has raised concerns, prompting many to question why infection rates tend to escalate during the winter season.

Trends of the past winter regarding COVID

Past COVID Trends During Winter

During the winter season, there’s traditionally been a correlation with increased instances of coughs, colds, and respiratory ailments. This is often attributed to factors such as the cold, dry air facilitating virus transmission, indoor gatherings leading to closer contact, and potential seasonal effects on the immune system’s response to infections.

Concerning COVID-19, there has been a consistent surge in cases during colder months. Reflecting on the pandemic’s onset, the SARs-COV-2 virus was initially identified in Wuhan, China, in December 2019, subsequently spreading globally and prompting widespread lockdowns. Presently, worldwide reported cases exceed 700 million, with India accounting for over 45 million cases, as reported by the WHO.

The winter of 2020-2021 saw a significant spike in COVID-19 cases globally, largely driven by the emergence of variants such as Alpha, Beta, and Gamma.

A year later, the highly contagious Omicron variant surfaced in Botswana and South Africa in late November 2021, swiftly becoming the dominant strain within a month, surpassing Delta.

According to WHO reports, there are now over 500 sub-lineages of the Omicron variant circulating, characterized by high transmissibility but generally milder symptoms compared to earlier variants.

The winter of 2022 witnessed the emergence of Omicron sub-variants like BA.2 and BA.5, which gained dominance with varying degrees of immune evasion and transmissibility, while no entirely new variants arose.

As of December 18, 2023, a new subvariant of Omicron has been classified by the WHO as a Variant of Interest (VOI), contributing to increased concerns in multiple countries.

The surge in COVID cases during the winter months is attributed to various factors

Why COVID Cases Surge During Winter

Dr. Joydeep Ghosh, an Internal Medicine Consultant at Fortis Hospital, Anandapur, Kolkata, shared insights with the OnlyMyHealth team regarding the increase in COVID cases during winter.

He pointed out that during winter, people tend to spend more time indoors with limited ventilation due to closed windows, which can lead to a higher concentration of viral particles in the air and facilitate transmission. Additionally, the virus can spread easily in enclosed spaces when individuals are in close proximity.

Another contributing factor, according to Dr. Ghosh, is the increased pollution levels during winter months. He noted that many people with colds and coughs visit doctors more frequently during this time, leading to more COVID testing and consequently more reported cases.

Why COVID Cases Surge During Winter

Dr. Ghosh also acknowledged that there may be a small number of unreported or misdiagnosed COVID cases during the summer months.

Regarding the current surge in COVID-19 cases, Dr. Ghosh suggested that year-end celebrations and festivities, which involve gatherings, parties, outings, and hotel stays, could be contributing to the rise in infections.

To mitigate the spread of COVID-19 amid rising infection rates, Dr. Ghosh emphasized the importance of avoiding crowded areas, maintaining physical distance, and staying in well-ventilated indoor spaces. He advised against closed, confined, or crowded spaces, echoing recommendations from the World Health Organization (WHO).

Can Immune System Be Compromised in Cold Temperatures

Does Immunity Weaken In Cold Temperature

Dr. Ghosh stated that the strength of one’s immunity is not linked to cold temperatures. He attributed the heightened risk during winter to increased pollution levels, explaining, “As pollution levels rise, so does the likelihood of contracting influenza or other respiratory infections. When the body fights off these infections, there’s a significant chance that immunity might decrease, making one more susceptible to illnesses like COVID-19.”


The global increase in COVID-19 cases may stem from various factors, including the emergence of the new subvariant JN.1 and seasonal changes like winter. To mitigate these risks, it’s important to take precautionary measures such as avoiding crowded places, practicing physical distancing, ventilating indoor areas by opening windows or doors, and steering clear of enclosed or densely populated spaces. Additionally, vaccination plays a crucial role in reducing the likelihood of severe COVID-19 infection, which can potentially result in hospitalization or death.