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Published on: Sep 01, 2021
3 minute read
By: Second Medic Expert

Why Do We Need Two Doses Of Vaccine?

Why do we need two doses of vaccine?

Vaccination is a two-fold protective measure for preventing illness. The first dose alerts the immune system to the presence of a certain virus or bacterium, and it creates a cellular immunity of sorts. The second dose is required to alert the body's antibodies, which are typically slower acting but more powerful bodies of defenses. These antibodies present themselves naturally in our bodies after vaccination, forming what we know as "natural specific immunity." To get that natural specific immunity from your second vaccination shot, you will need both injections at least six weeks apart. Essentially then, getting vaccinated twice in quick succession has no effect on your ability to build up natural specific immunity because you'll already be protected by cellular-specific immunity when you receive your second one.

The second dose helps to reduce the incidence of infectious disease. A major reason for a second dose is "herd immunity," in which a high proportion of people within a population have been vaccinated to provide what is known as "community protection" against an infection's spread. This limits the number of individuals who might otherwise be vulnerable or susceptible to contracting and transmitting infection. For this reason, everyone needs to do their part in making sure their own vaccinations are up-to-date and take care does not infect others when they're around them with compromised immune systems--primarily infants too young to have ever been vaccinated or anyone who cannot get vaccines for medical reasons such as being immunosuppressed.

The second dose of the vaccine introduces a different version of the virus into your system to allow your body to develop an immunity because not all viruses are 100% susceptible to the first vaccine.

The effectiveness of vaccination does decline over time, so another injection can help prolong immunity for 5-6 years before it's necessary to vaccinate again. It may be because there are different versions or "strains" or versions of viruses that vaccines don't always work well on. Or there are definitions for "immunity" that are different from ours - whether you have antibodies in your blood doesn't always show true protection against an infection! Of course, we recommend asking a medical professional if you're really interested in this question.

Reason #1: Whether an individual had natural immunity previously. The first shot could wear off for some people, so the second dose ensures that there is protection long after the first dose has worn off.

Reason #2: Some children do not develop strong enough immunity when given just one vaccine dose or they received their vaccines too early in life and later required a booster shot so the best way to protect them is with two doses.

Third Medic Medical consultation online To improve chances of inducing protective immunity in unvaccinated groups during outbreaks, it may be advisable to administer two doses of vaccines to maximize coverage among these populations The cold virus mutates extremely rapidly, and your chances of contracting a mutated strain of cold virus from the vaccine are higher if you skipped the first round. The goal here is to vaccinate as many people as possible with a vaccine that is most likely going to protect them from infection. That’s because even if 50% of those vaccinated this year will not be protected from contracting the disease, that 50% who do end up not being able to contract it are still more protected than they would have been had there been no vaccination. If you argue that vaccines don't work, then you are arguing that children should go untreated for deadly diseases because populations can never get rid of all illnesses at once!

This is a two-fold concern. First, we're aiming to create immunity against the disease more rapidly and it appears that this isn't accurate if we only vaccinate once; we need to boost with two doses at least one month apart. Second, because there are limitations in the science behind vaccination, it's difficult to tell who will have the highest reaction or reaction frequency. So for absolute safety, most doctors recommend three doses at any point in life for those who've never been vaccinated before

Second dose of the vaccine is to confer "immunity." If you happen to be exposed to a virus or bacteria and recover, your body will remember and create antibodies for that specific infection. A second dose of the vaccine provides enough time for those immunities to build up.

If you take the first dose, and go out right afterward to play with friends--this could lead the immune system into mistakenly attacking your own tissues as if they were infected as well because it doesn't yet know not them as healthy tissue.

The first dose is more or less a "primer" and the second dose corresponds with the timing of the typical infectious disease infection. Estimating how long it takes for immunity to develop also depends on which vaccine is being administered. Different viruses elicit variable immune responses, which means that they need different types of vaccines to work best. It's been found, for instance, that most people who receive an influenza vaccination require two doses about four weeks apart to fight off the flu properly. In addition, live attenuated influenza vaccine spurs fewer immunological side effects because it contains weakened versions of elements from virus strains already circulating among humans – since those factors are weaker than their intact counterparts found in a regular flu shot or nasal spray.

The two-dose vaccine regimen is a tried and tested method showing excellent effectiveness.

Read Blog

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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