Covid-19 vaccines work differently, largely safe for people with allergies

Can people with certain allergies be vaccinated with the Covid-19 vaccines? The Philippine Society of allergy, asthma and Immunology (PSAAI) recently released a position statement on the Covid-19 vaccines and the possible adverse reactions on people.

However, Dr. Marysia Stella Recto, immediate past president of PSAAI and a professor of adult and Pediatric allergy and Immunology at the University of the Philippines-philippine General Hospital (UP-PGH), said we must understand how Covid-19 vaccines work because different vaccines have different outcomes.

The viral vector and mrna vaccines were developed to produce spike proteins and once injected, it should develop an immune response. The others—whole virus and Protein sub-unit—will develop a more holistic immune reaction aside from the spike protein.

The nucleic acid vaccines or “genetic vaccines” (e.g., Pfizer and Moderna) use genetic material to make the Covid-19 protein, which is recognized by the immune system to trigger a response and build immune memory so the body can fight off the virus in the future. They are low cost, fairly fast to develop and should be stored in low temperatures.

Viral vector

THE viral vector vaccines use an unrelated harmless virus that was modified, in this case the modified Covid-19 genetic material, as a “delivery” virus known as “viral vector.” “Once introduced into the host, the vector will discharge the genetic material and the cells will now develop an immune response after the protein of the Covid-19 virus has been formed and generates a stronger immune response. examples are Gamaleya, astrazeneca, Cansino, and Janssen vaccines,” she said.

The Protein vaccines contain proteins from the virus used to trigger an immune response. They can be whole proteins, protein fragments or many protein molecules packed into nanoparticles. “They have good previous safety records, and usually used with an adjuvant ‘to boost efficacy.’ These are tried-and-tested vaccines like the Hepa B vaccines. examples are Sanofi/gsk and novavax,” she said.

The Whole viruses, one of which is the “Inactivated vaccines,” contain killed Covid-19 virus. Since it is a complete virus, it fights not just the spike proteins that it will develop antibodies to, but also the different portions of the virus and may need also need an adjuvant. Best example is the flu vaccine, and this is seen in Sinovac and Sinopharm vaccines.

The other whole vaccine is the “attenuated” type, which contains the weakened virus that is weak enough not to cause infection. Once injected, it will also cause a holistic immune response. It needs time and extensive testing, and the immune response resembles natural infection. example is the oral polio vaccine. The Codagenix vaccine was the one developed and is now in clinical trials.

Vaccine adverse events

THERE may be varying events after vaccination, such as the “reactogenic” and the “allergic” reactions. The “reactogenic” reactions may be “local” reaction (pain, swelling at injection site within the first three days) or the systemic reaction (headache, muscle pain, body aches, tiredness, fever and chills, and vomiting).

Reactions are usually mild to moderate and can be gone in three days. It can be managed by paracetamol, pain relievers, hydration, or cold compress. Factors that may induce “reactogenic” reactions may include vaccine (injection route, adjuvants, dose number), administration (needle length, rapid injection, administration route), and intrinsic (age, ethnicity, gender, Body Mass Index or BMI) factors.

“Reactions to Covid-19 vaccines may occur but not all reactions are allergic. While the majority of reactions are reactogenic, they are not the same as allergic reactions,” Dr. Recto added.

In terms of “allergic” reactions, mild allergic reactions may occur, such as rashes, itchy skin, runny nose, sneezing and are usually managed by antihistamines. But the concern of many, Dr. Recto said, is that they may develop severe allergic reactions to the vaccine, such as “anaphylaxis” but it is rare. In the two vaccines introduced first in the world, Pfizer reported only 11 cases in 1 million shots, while Moderna reported only 2.5 cases for the same number of shots.

Anaphylaxis

TO experience anaphylaxis, two or more symptoms such as hives/wheals, flushed skin, skin itch, swelling of face and throat, difficulty of breathing, wheezing, vomiting, abdominal cramps, dizziness, loss of consciousness, and abnormally fast heartbeat or “tachycardia” should manifest. These happen 30 minutes after injection but may happen after one to four hours and can be managed with epinephrine.

Recently, the World allergy Organization anaphylaxis Committee evaluated the different vaccines available and looked at their risks in developing anaphylaxis. The Coronavac from Sinovac and BBIBP-CORV from Sinopharm, the whole vaccines, reported no anaphylactic events during clinical trials.

The mrna vaccines (Pfizer and Moderna) also reported no anaphylaxis reactions during clinical trials. But when used it in real life, 1:100,000 patients developed it. “But take note that these vaccines contain Pegs or polyethylene glycol, which are known to cause allergies in patients who are allergic to laxatives, certain chemotherapy drugs or certain cosmetics,” Dr. Recto averred.

The viral vector vaccines like from astra Zeneca and Sputnik V (Gamaleya of Russia), which contain polysorbate 80, a preservative found in many other vaccines, had no anaphylactic incidents reported as well, but was also found to cross-react with Peg-allergic patients.

So who can really receive the Covid-19 vaccines?

PATIENTS with allergy to food (such as egg), inhalant allergens (dust mites, pollen, pets) and insect venom, eczema, asthma, rhinitis, hives or urticarial, or with history of rashes to oral medicines, may take the vaccine. So far, there are no contra-indications for allergic patients. However, for those with autoimmunity or immunodeficiencies, information is still lacking and immune response to vaccine may be reduced so we still have to wait for trials that are evaluating whether they can be given to those with immunodeficiency.

Who should NOT receive the vaccines?

THERE are only two contra-indications— a patient with immediate, or within four hours after vaccination, allergic reaction (mild to severe such as anaphylaxis) to the first vaccine dose, and those with a history of allergic reaction to Pegs or polysorbates. a person in this category should be referred to an allergist/immunologist for further evaluation or given a recommendation on what vaccine should be given.

The PSAAI document also included an allergy Risk assessment for Covid-19 vaccination where people can see the assessment for people with Low, Moderate, or High Risk classifications. It is available at the PSAAI web site, www.psaai.org.

The PSAAI web site also offers information and guidelines for vaccination, how to recognize whether to just give antihistamine, or what to do when anaphylaxis happens. “This is our help for our colleagues in the hospitals or vaccination centers to help recognize and manage anaphylactic or allergic reactions after vaccination.”

Overall, based on current data, the benefits of receiving Covid-19 vaccination far outweighs the risks of an allergic reaction, according to Dr. Recto. “a vaccine may have had five reactions in 1 million people, but people are 100 times more likely to die from Covid-19 than to have a serious allergic reaction to the vaccine.”