--- title: Potential Side Effects of COVID-19 Vaccines tags: live-v0.1, facts, vaccines permalink: https://c19vax.scibeh.org/pages/sideeffects --- <!---{%hackmd FnZFg00yRhuCcufU_HBc1w %}---> {%hackmd GHtBRFZdTV-X1g8ex-NMQg %} # The potential side effects of COVID-19 vaccines [TOC] ## Efficacy vs. side effects Our [facts page about the COVID-19 vaccines](https://c19vax.scibeh.org/pages/c19vaxfacts) highlights the efficacy of the three main vaccines available to date (Pfixer-BioNTech, Moderna, and Oxford-AstraZeneca) and explains how those data were obtained. All trials involved the same basic design: participants were randomly assigned to a control (placebo) group or to the vaccination group. The [Pfizer-BioNtech trial](https://www.nejm.org/doi/full/10.1056/NEJMoa2034577?query=featured_home) involved 43,448 individuals; the [Moderna trial](https://www.nejm.org/doi/full/10.1056/NEJMoa2035389?query=featured_home) involved 30,420 participants; and the [Oxford-AstraZeneca](https://linkinghub.elsevier.com/retrieve/pii/S0140673620326611) trial recruited 23,848 participants of whom 11,636 were included in the interim analysis that has been published. Altogether more than 80,000 people were enrolled in those trials, and so there was considerable opportunity to observe side effects. A useful summary of the known side-effects of the Pfizer-BioNTech and Oxford-AstraZeneca vaccines --- the two which are authorised for use in the UK as of 1st Jan 2021--- can be found in the [“Green Book”, which is a U.K. manual for healthcare workers who administer vaccines](https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/948757/Greenbook_chapter_14a_v4.pdf): > Local reactions at the injection site are fairly common after Pfizer BioNTech COVID-19 mRNA Vaccine BNT162b2, primarily pain at the injection site, usually without redness and swelling. Systemic events reported were generally mild and short lived (Walsh et al, 2020). In the final safety analysis of over 21,000 participants 16 years and older, the most common events were injection site pain (>80%), fatigue (>60%), and headache (>50%). Myalgia, arthralgia and chills were also common with fever in 10-20%, mainly after the second dose. Most were classified as mild or moderate. Lymphadenopathy was reported in less than 1%. (Polack et al, 2020). Four cases of Bell's palsy were reported in vaccine recipients in the trial. Although within the expected background rate, this will be monitored closely post-implementation. Side effects were less common in those aged over 55 than those aged 16 to 55 years. Severe systemic effects, defined as those that interfere with daily activity, included fatigue in 4% and headache in 2%. There was no signal to suggest that prior vaccination led to enhanced disease with only 1 case of severe COVID-19 in the 8 vaccine failures. (Polack et al, 2020). > > From early phase trials, mild pain and tenderness at the injection site was common with AstraZeneca COVID- 19 vaccine occurring in 88% of 18-55 year olds, 73% of 56-69 year olds and 61% of people aged 70 years or over; similar levels were reported after each dose. Short lived systemic symptoms including fatigue and headache were also common but decreased with age, being reported in 86%, 77%, and 65% of those aged 18-55, 56-69 and 70 years or over respectively; most of these were classified as mild or moderate. These reactions were unusual after the second dose (Ramasamy et al, 2020). Mild fever (>38 ̊C) was recorded in the first 48 hours for around a quarter of younger participants and but was not reported in those over 55 years of age or in any age group after the second dose (Ramasamy et al, 2020). Fever can be modified by the prophylactic use of paracetamol, which does not affect the immune response to this vaccine (Folegatti et al, 2020). In the phase 3 study, injection site reactions, mild fever, headache, myalgia and arthralgia occurred in more than 10% of vaccinees. Less than 1% reported lymphadenopathy or an itchy rash. Only one serious adverse event was reported as possibly linked to the vaccine; this was a case of transverse myelitis which occurred 14 days after dose 2. There was no signal to suggest that prior vaccination led to enhanced disease. (Voysey et al, 2020). **In a nutshell, the main side effects are pain at the site of the injection, headache, fatigue, muscle aches, fever and chills. These problems usually resolve after 1-2 days.** ## Severe allergic reactions (“anaphylaxis”) If 1,000,000 people get vaccinated (using any existing vaccine), [one person](https://vaccine-safety-training.org/anaphylaxis.html) can be expected to have a severe allergic reaction known as anaphylaxis. People who develop severe allergic reactions normally make rapid and full recoveries and the healthcare professionals who give vaccines are trained and equipped to manage these rare events. Severe reactions tend to occur very rapidly after injection. The rates of severe allergic reactions following the Pfizer-BioNTech and Moderna mRNA vaccines are also very low, but may be higher than seen for other vaccines. A recent study by [Banerji et al. (2020)](https://dx.doi.org/10.1016/j.jaip.2020.12.047) reported 10 severe allergic reactions after more than 2,000,000 vaccinations with the Pfizer-BioNTech vaccine, equating to a rate of around 1 in 200,000. None of those events entailed any long-term effects or fatalities, and all patients were treated immediately with complete resolution of symptoms. To guard against those unlikely events, people who receive these vaccines are asked to remain under observation for a period after the injection so that medical staff are on hand to help if they have a reaction. <!--- According to the live tracker https://ourworldindata.org/covid-vaccinations the total number of people who’ve been vaccinated is 13 million right now, it would be great to have an updated number of anaphylaxis cases as well. All I could find was this https://fortune.com/2020/12/31/everything-to-know-about-allergic-reactions-to-covid-vaccines/ which isn’t exactly hard data. ---> :::info To put this into context, about 5% of Americans (1 in 20) [have suffered anaphylaxis](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5589409/) from a variety of causes, including exposure to certain foods (e.g., nuts, seafood) or insect bites. The risk of anaphylaxis from the COVID-19 vaccine (1 in 200,000) is therefore **10,000 times smaller** than our background risk. ::: ## What about long-term side effects? Long-term side-effects cannot be evaluated until the appropriate time has passed since a large number of people has been vaccinated. In the trials to date, people were monitored for more than 3 months after they received the first dose. However, given the known risk that COVID-19 can cause long-term damage (see our [facts page about COVID-19](https://c19vax.scibeh.org/pages/covidfacts)), the risk of long-term side effects from the vaccines is likely to be far smaller. <!--- * There have been very rare side-effects to pregnant/breast-feeding women from vaccines while it is documented that they are [in higher risk than non-pregnant women of having serious health problems due to COVID-19](https://www.cdc.gov/mmwr/volumes/69/wr/mm6944e3.htm?s_cid=mm6944e3_w#contribAff). More research is conducted to investigate [potential side-effects to breast-feeding / pregnant women](https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/special-populations/pregnancy-data-on-covid-19/what-cdc-is-doing.html#:~:text=Based%20on%20what%20is%20known,outcomes%2C%20such%20as%20preterm%20birth.) and, as data from vaccinations accumulate, our knowledge increases. ---> ## Latest updates (January 2021 onward) The European Medicines Agency [released its first safety update](https://www.ema.europa.eu/en/news/first-covid-19-vaccine-safety-update-published) about the Pfizer/BioNTech vaccine on 29 January 2021. > "It concludes that safety data collected on Comirnaty use in vaccination campaigns is consistent with the known safety profile of the vaccine, and no new side effects were identified." Two items from the [detailed report](https://www.ema.europa.eu/en/documents/covid-19-vaccine-safety-update/covid-19-vaccine-safety-update-comirnaty-january-2021_en.pdf) are worth highlighting. * First, based on U.S. data, it reports the incidence of severe allergic reactions as being approximately 11 cases per million vaccinations. This is slightly higher than earlier estimates (see [above](https://hackmd.io/4OKKEkeBTb2WvIuOXOoiEg?both#Severe-allergic-reactions-%E2%80%9Canaphylaxis%E2%80%9D)), but is still small (around 1 in 100,000) and can be managed by healthcare professionals. * Second, the Agency reviewed a number of deaths following vaccinations that were reported in Norway and concluded that their "review did not suggest a safety concern." We have examined the issue of deaths following vaccinations [in detail on one of our Myths pages](https://hackmd.io/@scibehC19vax/misinfo_myths#FACT-Sadly-old-frail-and-vulnerable-people-sometimes-die). We will report further updates from public-health agencies as they become available. ---- <sub>Page contributors: Stephan Lewandowsky, Adam Finn</sub> {%hackmd GHtBRFZdTV-X1g8ex-NMQg %} {%hackmd oTcI4lFnS12N2biKAaBP6w %}