Everything You Need to Know About Vaccine Safety and Effectiveness

A year and a half ago the world was thrust into a pandemic on an unprecedented scale. With no vaccines against the novel virus, scientists, doctors, ethics approval boards, manufacturers, and regulatory agencies cooperated globally to find a way to immunize people as quickly as possible in a race to get the world “back to normal.”

Today, more than 19 vaccines have been rolled out across the globe with more brewing in the pipeline in an effort to stop the spread of the disease. The speed of the rollout had many expressing concern about how quickly the vaccines were developed, how safe and effective they might be, what side effects to look out for if vaccines are being distributed fast enough, and when herd immunity will be achieved. This new state of worry and uncertainty has been dubbed “vaccine anxiety” and it is a normal reaction to the new and unfamiliar.

Read on for everything you need to know about vaccine safety and effectiveness.

What do vaccines actually do?

Vaccines stimulate the immune system to recognise harmful pathogens so that the body can produce antibodies to fight off infections. Vaccines do not “kill the virus”.

Can’t the immune system fight the virus on its own?

Yes, it can, but it takes time for the immune system to recognise a novel pathogen as harmful and to build up sufficient antibodies to fight the virus. Until then, the virus is left to multiply unchecked.

Compromised immune systems are particularly vulnerable. Vaccines fast-track the process.

Can people with allergies get vaccinated?

Yes, most people who have allergic reactions may get vaccinated. There is a 30-minute observation period after vaccination. Vaccine centres have safety protocols in place to respond to any adverse reactions.

Those who have severe allergic reactions that could result in anaphylactic shock or hospitalisation are encouraged to consult with a healthcare provider to assess risk prior to receiving their COVID-19 vaccine.

Should those with autoimmune diseases or weakened immune systems be vaccinated?

People who are immunocompromised or have an autoimmune disease are at higher risk for severe illness from COVID-19. While vaccination is recommended in most cases, it is best to consult with a healthcare provider to discuss the risks and benefits of vaccination.

Compromised immune systems may also experience a reduced response to the vaccine. Those vaccinated will need to continue to follow all current guidelines to protect themselves against the virus.

What about people managing chronic conditions?

Individuals with existing or underlying comorbidities such as heart disease, obesity, diabetes, or hypertension are considered high risk. Having one or more non-communicable chronic diseases has a higher chance of mortality and is associated with severe symptoms that need to be treated in intensive care or by being placed on oxygen support. People with chronic conditions are strongly encouraged to get vaccinated as it can reduce the severity of the symptoms and their risk of death.

What about pregnant and breastfeeding mothers?

Pregnancy increases the chances of severe complications from COVID-19. Vaccination is unlikely to pose a risk for those who are pregnant or breastfeeding. Consult a healthcare provider to discuss the benefits and risks of being vaccinated.

Early data demonstrate a higher secretion of protective antibodies in the breastmilk of mRNA-vaccinated mothers suggesting a potential protective effect for the breastfed infant.

Can those who have already recovered from COVID-19 be vaccinated?

Yes, though the effect and protectivity of the antibodies that develop in response to a COVID-19 infection are still being studied. Those who previously had COVID-19 can and should get vaccinated to protect against reinfection from new variants and to help build herd immunity.

Why are people still getting infected even after being vaccinated?

Vaccines do not “kill the virus”. They give the body a higher chance of fighting infections, avoiding serious complications, and recovery. In May 2021, a city in Brazil with approximately 45,000 residents reported a 95% drop in the death rate and 80% reduction in hospitalisations after more of their adult population got vaccinated

How were the vaccines developed so quickly?

The urgency of the pandemic prioritised the development, testing, evaluating, and reviewing of the vaccines. Funding, knowledge sharing, parallel trials, and streamlined regulatory approval all played a part in the development of vaccines. Also, the high number of infections allowed for extensive testing, accelerating the process.

Why are there different vaccines?

All vaccines prepare the body to recognise and overcome viruses. The main differences are in the way they are made and the way they stimulate the immune system.

How do different types of vaccines work?

There are four main types of COVID-19 vaccines, each stimulating the immune system differently.

1. Inactivated
   This vaccine technology uses a weakened or inactivated form of the pathogen to introduce the virus to the immune system. It is viewed as a more “conventional” or “safe” form of vaccine as the technology used has been well established for other diseases and is suitable for most people, even those with compromised immune systems. It is also relatively easy to manufacture but may require booster shots.
   Other licensed vaccines that use this type of technology: Hepatitis A, polio, rabies

2. Protein Subunit
   These vaccines only contain “parts” of a pathogen to trigger an immune response. Protein subunit vaccination is also well established and can minimise the risk of side effects making it potentially advantageous for weakened immune systems. It is relatively complex to manufacture, and adjuvants and booster shots may be required.
   Other licensed vaccines that use this type of technology: Hepatitis B, meningococcal disease, pneumococcal disease, shingles

3. Viral vector
   Introduces a safe, modified version of the virus known as the “vector” that delivers genetic code to produce antigens. These antigens then trigger an immune response to fight off the virus. In a COVID-19 vaccine, the vector is the spike protein found on the surface of the virus. This is another well-established vaccine technology.
   Other licensed vaccines that use this type of technology: Ebola

4. Nucleic acid / mRNA
   Though there are no existing licensed or approved vaccines that use this technology, a number of mRNA vaccines have been studied for decades against influenza, rabies, and the Zika virus. This vaccine uses mRNA molecules made in a lab that code parts of the virus. It instructs cells to produce antigens which trigger an immunising response. It does not affect DNA.

What about side effects?

Common short-term side effects of all vaccines include:

• Pain, swelling, or redness at the injection site

• Chills and fever

• Nausea, diarrhoea, or vomiting

• Tiredness, headaches, and joint pain

Severe side effects like the narrowing of the air passageway and blood clots are rare.

Long term side effects remain to be seen. Existing vaccinations for other diseases have proven safe and effective in eradicating and suppressing outbreaks without any side effects in the long run.

Which vaccine works the best?

Short answer: The one you get.

Getting vaccinated will help the immune system fight off the virus. While no vaccine is 100% effective, it reduces the risk of serious illness or complications and death. Vaccinations also build herd immunity thereby protecting children and those who are unable to get vaccinated from falling ill.

It is normal to feel nervous or anxious about getting vaccinated. COVID-19 has upended so much of our lives with uncertainty it can be difficult to make head or tail of a situation. Check with your medical advisor about the safety and efficacy of the vaccine.