How does COVID-19 vaccine actually interact with the body once it is injected into the upper arm?
Two experts are of the view that while the vaccine doesn’t contain any live COVID-19 virus, it teaches the human immune system to protect against it.
Dr. M. Fahad Khalid, chief of the Division of Hospital Medicine at Penn State Health Milton S. Hershey Medical Center, and Dr. Mohammad Ali, an infectious diseases physician at Penn State Health Holy Spirit Medical Center said so.
But, according to guidance released by the American College of Allergy, Asthma & Immunology (ACAAI), allergic reactions to vaccines are generally rare and people with common allergies are not more likely to have a reaction to the Pfizer-BioNTech COVID-19 vaccine, .
The ACAAI COVID-19 Vaccine Task Force issued the guidance related to the risk for an allergic reaction with the Pfizer-BioNTech COVID-19 vaccine that was given emergency use authorisation by the US Food and Drug Administration last December 11.
Members of the task force say that individuals with common allergies to medications, foods, inhalants, insects, and latex are no more likely than the general public to have an allergic reaction to the Pfizer-BioNTech COVID-19 vaccine.
However, the task force does not recommend the Pfizer-BioNTech COVID-19 vaccine for individuals with a known history of a severe allergic reaction to polyethylene glycol, a component of this vaccine that is known to cause anaphylaxis.
Regardless of patient history, all vaccine administration should occur in a health care setting where anaphylaxis can be treated.
Relatedly, all individuals should be monitored for adverse reactions for at least 20 to 30 minutes after injection. Epinephrine should serve as the first-line treatment for any anaphylactic reactions.
“The Pfizer-BioNTech COVID-19 vaccine is not a live vaccine and it can be administered to immunocompromised patients”, according to the task force.
“Physicians and other providers should inform such immunocompromised patients of the possibility of a diminished immune response to the vaccine. We do not know at this time if people with a weakened immune system will respond to the vaccine and be protected from COVID-19.”
Both vaccines —the Pfizer-BioNTech and Moderna vaccines—are mRNA (messenger RNA) vaccines. They are not live viruses. Instead, they work by giving your body a blueprint to create a piece of the virus that causes COVID-19, called a spike protein.
Once you receive the vaccine, your cell’s machinery uses the mRNA instructions to make the spike protein. This protein is then displayed on the cell surface, and the immune system sees it and responds to it.
While mRNA is a type of genetic code, it never enters the center (nucleus) of your cells. “That means it never converts into DNA”, Khalid said. “The mRNA itself is destroyed by the cells after they produce the spike protein.”
The spike protein the vaccines create is the same one found on the surface of the virus that causes COVID-19. However, the vaccines do not contain any live virus. “The spike protein itself cannot cause an infection”, Ali said.
Khalid and Ali also addressed many common questions people have about both vaccines:
Safety of vaccines
Advances in vaccinology and vaccine production allowed pharmaceutical companies to create vaccines in months. However, both vaccines followed rigorous FDA guidelines, including the normal regimen of clinical trials and Phase 1, 2 and 3 trials.
“Their effectiveness is tremendous”, Ali said. “The flu vaccine is typically 40% to 60% effective, and the COVID-19 vaccines are 94% to 95% effective.”
The Centers for Disease Control and Prevention (CDC) reports a limited number of incidents where people experienced a severe allergic reaction (anaphylaxis) or reaction such as hives, swelling or wheezing.
The CDC recommends against people taking the vaccine who had a prior severe allergic reaction to any ingredient in the COVID-19 vaccine. People who have had allergic reactions to other vaccines should ask their doctor about taking the COVID-19 vaccine.
People with nonvaccine-related allergies—food allergies, pet allergies, seasonal allergies—are safe to get vaccinated, says the CDC.
Possible side effects, such as swelling or pain at the injection site, fever, headache or muscle pain, are temporary. “Those side effects aren’t nearly as bad as severe cases of COVID-19, which can be fatal,” Khalid said.
Currently, the CDC recommends vaccination even in people who have had COVID-19 in the past. This is because we do not know how long immunity to the virus lasts after someone is infected.
Do I need to wear a mask after getting the COVID-19 vaccine? Yes, you must continue to wear a mask, practice social distancing and continue to wash your hands. The vaccine protects you from getting sick with COVID-19, but researchers still don’t know if individuals can still get infected and transmit the virus to others.
The vaccine also will not cause infertility. “There’s a lot of misinformation out there,” Ali said. The most trustworthy resource for accurate information is the CDC website.
Alison Enimpah, a registered nurse who provided direct care for COVID-19 patients at the Milton S. Hershey Medical Center, was among the earliest group of health care workers to get vaccinated. She’ll receive her second dose later this month.
“The vaccine adds a layer of reassurance that we’re making forward progress in keeping ourselves and our community safe during the pandemic”, she said.