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Expected Symptoms from COVID-19 Vaccine: Here’s How to Counsel Recipients

A high percentage of people showing up to be vaccinated against COVID-19 at pharmacies are likely to be apprehensive about side-effects and hypersensitivity reactions. Here’s what pharmacists can tell them about expected responses – which usually are mild and time-limited -- and the best way to treat any uncomfortable symptoms.

ATLANTA – Social media is filled with stories about what happens after receiving the second COVID-19 vaccination shot, whether written by those who are gloating they didn’t feel a thing or others complaining that they were too sick to get out bed for days.

The truth usually lies somewhere in between, but pharmacists and other vaccinators need to be prepared to address recipients’ concerns.

“Before vaccination, providers should counsel mRNA COVID-19 vaccine recipients about expected local (e.g., pain, swelling, erythema at the injection site, localized axillary lymphadenopathy on the same side as the vaccinated arm) and systemic (e.g., fever, fatigue, headache, chills, myalgia, arthralgia) post-vaccination symptoms,” according to guidance from the national Centers for Disease Control and Prevention. “Depending on vaccine product (Pfizer vs. Moderna), age group, and vaccine dose, approximately 80–89% of vaccinated persons experience at least one local symptom and 55–83% experience at least one systemic symptom following vaccination.”

Public health officials point out that most systemic post-vaccination symptoms are mild to moderate in severity, occur within the first three days of vaccination, and resolve within 1–3 days of onset.

The symptoms are more frequent and severe following the second dose and among younger persons compared with older persons, defined as older than 55 or 65 and older for Pfizer-BioNTech or Moderna vaccines, respectively.

“Unless persons experience a contraindication to vaccination (see below), they should be encouraged to complete the series even if they experience local or systemic symptoms following the first dose to optimize protection against COVID-19,” the CDC advises.

That includes recipients who only developed a delayed-onset local reaction – involving erythema, induration and pruritus -- around the injection site area after the first vaccine dose. Those do not have a contraindication or precaution to the second dose, according to the recommendations, which adds, “Delayed-onset local reactions have been reported in some individuals, including in Moderna clinical trial participants, beginning a few days through the second week after the first dose, and are sometimes quite large. It is not known whether persons who experienced a delayed-onset injection site reaction after the first dose will experience a similar reaction after the second dose. However, these delayed-onset local reactions are not felt to represent a risk for anaphylaxis upon receipt of the second dose. Thus, individuals with such delayed injection site reactions after the first mRNA COVID-19 vaccine dose should receive the second dose using the same vaccine product as the first dose and at the recommended interval, and preferably in the opposite arm.” .

In clinical trials, the article points out, hypersensitivity-related adverse events were observed in 0.63% of participants who received the Pfizer-BioNTech COVID-19 vaccine and 1.5% of participants who received the Moderna COVID-19 vaccine, compared with 0.51% and 1.1%, respectively, in the placebo groups.

Anaphylaxis following vaccination was not observed in the Pfizer-BioNTech or Moderna COVID-19 vaccines clinical trials but have very rarely been reported following receipt of mRNA vaccines since, the CDC writes.

How should pharmacists advise recipients on dealing with side-effects or hypersensitivity reactions.

The new guidance suggests that antipyretic or analgesic medications (e.g., acetaminophen, non-steroidal anti-inflammatory drugs) can be used, if medically appropriate, for post-vaccination local or systemic symptoms. The CDC doesn’t recommend, however, the use of routine prophylactic administration of the medications to prevent post-vaccination symptoms, It adds that information on the impact of such use on mRNA COVID-19 vaccine-induced antibody responses is not available at this time.

Also not recommended is the administration of antihistamines to COVID-19 vaccine recipients prior to vaccination to prevent allergic reactions. “Antihistamines do not prevent anaphylaxis, and their use might mask cutaneous symptoms, which could lead to a delay in the diagnosis and management of anaphylaxis,” public health officials explain.