Mobile Menu

The vaccine rivalry: Analyzing reported symptoms for each brand

Are you team Pfizer, Moderna or are you a Johnson & Johnson fan? As if there wasn’t enough division in the world, vaccine rivalries is now a thing. 

Even though most people have no choice as to what vaccine brand they receive, the internet has opinions, and these opinions are often rooted in the side-effects associated with each vaccine brand.

Full disclosure: While I am a member of the Moderna gang, this analysis will be approached with true scientific objectivity. Using a social listening platform, I pulled a sample of global tweets mentioning the names Moderna, Pfizer, Johnson & Johnson or AstraZeneca in addition to the word symptom. 

I then uploaded that file directly to Relative Insight, and compared the four brands against one another. Relative’s technology highlights the words, phrases, grammar, topic and emotion unique to conversations around each vaccine brand. This form of text analysis will uncover which symptoms are primarily associated with each vaccine.


Tweets mentioning the words Pfizer and symptoms, were more likely to mention arm soreness than about any of the other brands. Vaccine recipients used the phrases slightly sore arm, sore arm and soreness around when describing their Pfizer symptoms. Although this is an extremely common side-effect well documented in the press, Pfizer recipients were more likely to report it on Twitter.

Tweets about Pfizer were also more likely to mention the word period, specifically the period-like symptoms that many women reported to experience after their shot. While more research is needed, some women have also reported changes to their menstrual cycle after receiving the COVID-19 vaccine. 


The list of symptoms we found unique to Moderna recipients described what’s as what known as “Moderna arm” or “covid arm”, which results in a rash. Our analysis found Moderna side effects were more likely to be discussed using words like itchy, swollen, rash and redness around the vaccination site than for any of the other brands.

Moderna recipients had one common tip for beating these side effects: “Drink water”. We noticed these people far more likely to talk about water and encourage hydration to reduce unpleasant side-effects. In addition to getting lots of sleep and sticking to a healthy diet, doctors suggest staying hydrated pre and post-vaccination in order to minimize pain and fatigue. It’s interesting to see how well this professional advice landed with the general public. 


Symptoms associated with AstraZeneca resembled those of a common cold, and recipients were more likely to mention words like aching and runny in relation to their eyes and nose when discussing their post-vaccine state. Luckily, these reported symptoms were also described as moderate, but some recipients experienced a delay in symptom appearance as demonstrated by the prevalence of the phrase symptom appeared. Recipients used this phrase to communicate when they began to experience symptoms, as it took longer than expected.

Johnson & Johnson

J&J recipients on the other hand, were more likely to report severe symptoms or multiple symptoms. This set of people were infinitely more likely to use prefix phrases like ‘almost every’ and ‘got super’ in addition to their generic descriptions of side-effects like sickness or flu. The use of maximizing adjectives like every, super and really highlight the intensity of symptoms like exhaustion, earaches, loss of appetite and dizziness.

Although recently re-approved by the FDA, Johnson & Johnson administration was briefly paused by the US government for concerns over rare yet fatal blood clotting issues. The recent popularity of this news story created greater conversation using words like blood and clotting in reference to the J&J vaccine.

Don’t let this scare you! It’s important to remember vaccine side effects are entirely normal and expected. In fact, they’re a good thing – it means your immune system is working. Everyone responds differently, and a recent study found 75% of COVID-19 vaccine recipients did not experience side effects other than a sore arm. 

Language comparison has the power to uncover surprising bits of brand or audience analysis. Relative Insight works with any textual data source to compare conversation over time and location, across brands or demographics.

This form of analysis extracts the most value from written data sources, leading to powerful social insights and effective marketing communications.

Learn how Relative Insight can help your brand or agency