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Published on: Jul 07, 2020
1 minute read
By: Dr Rajan Choudhary

Asymptomatic Carriers Of COVID

Why Asymptomatic carriers of COVID are as dangerous as symptomatic patients

Many countries have now begun enforcing masks for everyone to wear when out in public, in enclosed spaces, or on public transport. There is good evidence to support these measures, but unfortunately, some still show resistance to the idea. Whilst some reasons put forward are non-sensical (masks do not cause any noticeable or measurable decrease in oxygen delivery to the body), other people feel like they shouldn’t wear a mask because they do not have symptoms of COVID. And thus would not spread anything. Here we look at a recent publication in Nature, one of the most esteemed peer-reviewed scientific journals in the world, and what it shows us about the transmission of COVID in a population.

This study by Lavezzo et al looked at the suppression of the SARS-CoV-2 outbreak in the Italian municipality of Vo’. This municipality is 50 kilometers west of Venice with a population of just 3,416 people. It experienced its first casualty of COVID on the 21st of February, after which it underwent lockdown for 14 days. During this time data was collected on the clinical presentation and hospitalization of COVID patients, as well as other citizens through the contact tracing network.

In total 2,812 residents were tested in late February, with another 2,343 tests performed two weeks later at the end of lockdown. Nasal and throat swabs were taken to identify infected individuals. The study found only 2.6% of people were positive for COVID at the start of lockdown, which reduced to 1.2% two weeks later.

Out of this infected population, 42.5% were asymptomatic. They had no symptoms at the time of swab testing nor did they develop symptoms afterwards. When the viral load was measured between symptomatic and asymptomatic patients, there was little difference.

Evidence has pointed to a large asymptomatic population, and previous studies have shown it to be as high as 50% in some cases. Many would assume if a patient has no symptoms then they must have fought the infection before it became an issue, or had a very low viral load and therefore were not likely to spread it. This study shows it is simply not true. Asymptomatic carriers of COVID are likely to contribute to the transmission and spread of COVID amongst the population.

If you are asymptomatic you have as high a viral load as someone who is symptomatic. But there is no way to tell without a swab. You have as much of a potential to spread the infection to the vulnerable. Even in people who became symptomatic the height of transmission was found to be before the patient showed any symptoms.

So what does this mean? If you have COVID you are likely to spread it before you show any symptoms or any symptoms at all. We know masks are effective at significantly reducing the spread of COVID, by catching the water droplets that carry the SARS-CoV-2 Virus. Now that shops and public places are re-opening, the risk of spread is high.

Wear a mask. Stop the spread.

https://www.nature.com/articles/s41586-020-2488-1_reference.pdf suppression of a SARS article

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How Cold Weather Affects Health: Understanding Winter’s Impact on the Body

Seasonal changes influence human health more than most people realise. Cold weather, in particular, places unique stress on the body and can worsen existing health conditions while increasing susceptibility to new illnesses. Understanding how cold weather affects health is essential for preventing seasonal complications and maintaining wellbeing during winter months.

In India, winter-related health issues vary by region but commonly include respiratory infections, cardiovascular strain and joint discomfort. According to the Indian Council of Medical Research (ICMR) and World Health Organization (WHO), cold exposure is associated with increased morbidity, especially among older adults and people with chronic conditions.

Why Cold Weather Impacts the Body

The human body works constantly to maintain core temperature. In cold environments:

blood vessels constrict to conserve heat
energy expenditure increases
immune responses may weaken
organs work harder to maintain balance

These adaptations, while protective, also create health vulnerabilities.

Increased Risk of Infections

Weakened Immune Response

Cold weather can suppress immune function, making it harder for the body to fight infections.

Factors contributing to winter infections include:

reduced vitamin D due to less sunlight
dry air affecting mucosal defenses
closer indoor contact

Common winter infections include colds, flu and respiratory illnesses.

Respiratory Health Problems

Cold air irritates the respiratory tract.

This can lead to:

worsening asthma symptoms
bronchitis flare-ups
increased cough and breathlessness

WHO reports higher hospital admissions for respiratory illnesses during colder months.

Impact on Heart Health

Cold temperatures affect cardiovascular function.

Blood Vessel Constriction

Cold causes blood vessels to narrow, increasing:

blood pressure
heart workload

This raises the risk of:

heart attacks
strokes

People with existing heart disease are particularly vulnerable.

Joint and Muscle Pain

Cold weather affects musculoskeletal health.

Common complaints include:

joint stiffness
muscle aches
worsening arthritis pain

Lower temperatures reduce joint lubrication and increase sensitivity to pain.

Metabolic and Weight Changes

Winter often leads to:

reduced physical activity
increased calorie intake
metabolic slowdown

These changes contribute to weight gain and worsen metabolic conditions such as diabetes.

Skin and Hydration Issues

Cold air holds less moisture.

This leads to:

dry skin
cracked lips
worsening eczema

Dehydration is also common as thirst perception reduces in cold weather.

Mental Health Effects

Seasonal changes can influence mental wellbeing.

Cold weather is associated with:

low mood
reduced motivation
seasonal affective symptoms

Limited sunlight affects circadian rhythm and serotonin levels.

Cold Weather and Older Adults

Elderly individuals face higher risks due to:

reduced temperature regulation
weaker immunity
existing chronic conditions

Winter-related complications are a significant cause of hospitalisation in older populations.

Why Chronic Diseases Worsen in Winter

Conditions such as:

hypertension
arthritis
asthma
diabetes

often worsen due to reduced activity, stress on organs and infection risk.

Preventive Strategies for Winter Health

Maintain Body Warmth

Layered clothing and warm environments reduce cold stress.

Support Immunity

Adequate nutrition, vitamin intake and sleep strengthen immune defences.

Stay Physically Active

Indoor exercises and regular movement prevent stiffness and metabolic decline.

Manage Chronic Conditions

Regular monitoring and medication adherence are critical during winter.

Hydration and Skin Care

Drinking fluids and using moisturisers prevent dehydration and skin damage.

Role of Preventive Healthcare

Preventive healthcare helps:

identify seasonal risk factors
adjust treatment plans
prevent winter complications

NITI Aayog highlights seasonal preparedness as an important public health strategy.

When to Seek Medical Help

Medical attention is necessary if:

infections persist or worsen
chest pain or breathlessness occurs
joint pain limits mobility
mental health symptoms interfere with daily life

Early care prevents serious outcomes.

Long-Term Impact of Ignoring Winter Health Risks

Ignoring cold weather effects may lead to:

severe infections
cardiovascular events
chronic pain progression
reduced quality of life

Seasonal awareness plays a critical role in long-term health.

Conclusion

Understanding how cold weather affects health allows individuals to take timely preventive measures. Winter increases the risk of infections, heart strain, respiratory problems, joint pain and mental health challenges. With proper warmth, nutrition, activity and preventive healthcare, most cold-related health issues are manageable and preventable. Seasonal care is not optional—it is essential for protecting health and wellbeing throughout the colder months.

References

ICMR – Seasonal Health and Infectious Disease Reports
National Family Health Survey (NFHS-5) – Seasonal Morbidity Data
NITI Aayog – Preventive Healthcare and Seasonal Preparedness Strategy
WHO – Cold Weather and Health Impact Guideline
Lancet – Seasonal Variation in Cardiovascular and Respiratory Diseases
Statista – Winter Health Trends and Illness Data
Indian Journal of Public Health – Climate and Health Studies

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