Vaccines: Side Effects and Concerns

Dr Sandeep Panikkasseri Dasan, Mbbs, Md, Mrcpch, Specialist Paediatrician, Aster Clinic Muhaisnah 

Vaccines are the most valuable contribution of medical science to mankind. Today, all nations are trying their best to get every resident vaccinated at the earliest in a race against the Covid pandemic. And we know that vaccines are winning the race in countries that managed to accelerate the coverage of vaccines among the public, anticipating further waves of the pandemic. Even with the rise of many variant strains of Covid, those vaccinated can avoid serious and life-threatening symptoms. It has allowed the easing of tighter restrictions giving hope and freedom to many. So, when most of us don’t doubt vaccine effectiveness, many are still concerned about side effects. And when misinformation is so readily accessible and so widely disseminated, it’s becoming an increasing challenge to keep the early momentum of vaccination programs going. It’s important to avoid extrapolating data of Covid vaccine side effects, to those among other vaccines already in use including the universal childhood vaccines. Covid is new to us so are the vaccines against them and international bodies including WHO is closely monitoring for any unexpected side effects after vaccination.

How do Covid-19 vaccines work?

To know more about side effects, it’s important to know how vaccines work. Vaccines introduce our immune system to a part of the pathogen (virus) known as antigen and thereby trains our body to produce an immune response to fight off the infection. The antigen can be a weakened or inactivated virus, or it might be one part of the pathogen like the spike protein on the surface of SARS CoV 2. Traditional vaccines deliver antigens directly to the body, whereas newer mRNA (Pfizer and Moderna) and DNA (Astrazeneca) vaccines contain a genetic blueprint (set of instructions) that tells the body to make the spike proteins using the body’s cells.

When the vaccine is injected, it activates the innate immune response with “watchdog” cells macrophages, and dendritic cells that screen the blood for suspicious signs. The former eats up dead cells and the latter collects information about the unwanted intruder and informs the adaptive immune system (producing antibodies). The cells, when they sense danger; release a group of proteins called cytokines which act on blood vessels to make them wider and helps deliver other immune cells for backup. The innate immune response unfolds over a few hours to days and may sometimes result in flu-like symptoms like headache, fever, muscle, and joint pain, or swelling and pain at the vaccination site. These side effects are designed to aid immune response and are a healthy sign that the immune system is working. These symptoms subside in a day or two because the body’s response to vaccination is self-limiting. For eg, the body only makes as much spike protein as the blueprint in the vaccine allows. But with natural infection, the virus is going to keep multiplying taking along the body’s immune response and inflammation until one of them wins over the other. A common concern raised among people is the person getting positive for Covid after Covid vaccination. There is no doubt about the fact that the Covid vaccine cannot give Covid infection as it’s not the virus that is injected. When the prevalence of the infection is high with community spread, it’s natural that the person can get infected at any time.

Why do side effects vary in different people?

Experts say younger people who have more robust immune systems and those who had previous exposure to the pathogen/virus are more likely to report side effects. Our genetics and overall health play a role in our response to a vaccine and virus. Some of us may be better or worse at making those cytokines.

These common side effects can be managed easily with paracetamol available over the counter. In addition to the above common side effects, anaphylaxis and allergic reactions are extremely rare side effects of vaccines. Their risk is higher among people with a history of allergies in the past. They are often immediate reactions and could be easily detected and treated in a medical setting. Hence, it’s important for all vaccinated to remain at the vaccination center for at least 10 to 20 minutes to observe for any immediate reactions.

Also, an absence of side effects is not a sign the vaccine is not doing its job. According to recently published research, people who don’t experience side effects from the mRNA Covid vaccine, still produce a robust antibody response. Hence Vaccines are safe and are designed after extensive trials to give a person immunity without the dangers of getting the disease and untoward side effects.