Table 1.

Six themes related to COVID-19 vaccination, along with the respective topics and sample tweets (N=672,133).

Theme and topics (keywords)			Sample tweet		Prevalence, %		Sentiment scorea
Theme 1: emotional reactions related to COVID-19 vaccines
	Topic 37: feeling hopeful after receiving COVID-19 vaccines (be, shot, get, feel, go, ready, see, happy, hope, and friend)	“Cried happy tears seeing family and friends abroad getting their COVID19 vaccines. Better days ahead”		3.2		+0.262
	Topic 30: feeling excited after receiving COVID-19 vaccines (get, receive, give, do, administer, complete, delay, deliver, waste, and order)	“Perks of completing the COVID19 vaccine series... we got a sticker!!.”		2.6		+0.097
	Topic 18: feeling angry toward politicians for claiming COVID-19 as a hoax (think, people, anti, right, believe, know, hoax, should, thing, and politician)	“Wow, wow majority of Republican house and senate are vaccinated. They are the one who denied that coronavirus existed and is a hoax. My, my they are the first one in the queue. They should not be in the queue at all if they believe coronavirus is a hoax.”		2.6		–0.109
	Topic 17: feeling angry toward President Trump for claiming COVID-19 as a hoax (want, go, would, Trump, will, name, Americans, credit, let, and people)	“The scientists developed the vaccines not the Trump Administration. The Trump Administration is responsible for 300,000+ deaths of Americans due to their incompetency and lying about the Coronavirus for months. Trump called the virus a Democratic HOAX!”		2.3		–0.110
	Topic 42: feeling thankful toward scientists who were involved in the development of COVID-19 vaccines (news, thank, end, day, science, Moderna, team, work, Pfizer, and job)	“Thank you thank you thank you for my covid-19 vaccine today. I feel extremely lucky and grateful. Thank you to the scientists and everyone behind rolling out the vaccine. In a world of darkness there is light at the end of the tunnel”		2.2		+0.482
	Topic 59: plea to stay vigilant even with the rollout of COVID-19 vaccination (mask, keep, continue, stay, social, wear, hand, safe, distance, and wearamask)	“Please remember control of COVID is in our hands- hands that put on our masks, the hands we sanitize and hands to maintain our spacing. Vaccines are coming but we cannot let our collective guard down!”		2.2		+0.175
	Topic 40: feeling proud to have contributed to the development of COVID-19 vaccines (part, share, late, thank, volunteer, experience, involve, learn, help, and successful)	“We’re proud to have played a part in the successful development of COVID19 vaccine.”		1.5		+0.409
	Topic 33: feeling frustrated about the inequitable access of COVID-19 vaccines (should, person, last, member, chief, resident, mandatory, people, outbreak, and medical)	“‛r there no workhouses?? r there no prisons??’ Prisons are Covid-19 hotbeds. When should inmates get the vaccine?”		1.4		–0.028
	Topic 55: feeling angry over the antivaccine movement and conspiracy claims (claim, conspiracy, misinformation, Twitter, dangerous, theory, medium, true, truth, and Bill_Gates)	“Sad that there even have to be articles like this to rebut the right-wing and anti-vaxer nonsense: No, COVID-19 vaccines don’t contain Satan’s microchips (and other scary conspiracy theories aren’t true either)”		1.4		–0.188
Theme 2: public concerns related to COVID-19 vaccines
	Topic 19: concerns about death related to COVID-19 vaccines (people, die, many, more, kill, number, infect, most, death, and will)	“People are known to die from so many illnesses. Millions die each day, so many die suddenly. Imagine people who were supposed to die suddenly on a particular day having recieved Covid-19 vaccine on the preceding day, many of them will try to blame Covid-19 vaccine”		2.3		–0.241
	Topic 11: concerns about the impact of COVID-19 vaccines on fertility (mRNA [messenger RNA], work, safety, efficacy, base, explain, research, datum, understand, and thread)	“It is UNKNOWN whether COVID-19 mRNA Vaccine BNT162b2 has an impact on fertility. Animal studies into potential toxicity to reproduction and development have not been completed”		2.1		+0.236
	Topic 26: concerns about misinformation related to COVID-19 vaccines (good, great, news, big, bad, fake, break, welcome, sell, and wake)	“Fed up of: lies lockdown FAKE NEWS covid vaccine coronavirus”		1.8		+0.206
	Topic 12: concerns about insufficient supply of COVID-19 vaccines (supply, have, run, hold, problem, try, demand, due, lack, and could)	“New York City could run out of COVID19 vaccines as early as next week. We need the federal government to act NOW.”		1.6		–0.057
	Topic 31: concerns about delays in vaccine rollout amid rising deaths related to COVID-19 (death, case, story, record, rollout, top, more, rise, and us)	“The US set a new record for coronavirus deaths reported in 24 hours with more than 3,700 on Wednesday amid troubles with the vaccine rollout. The harrowing tally from Johns Hopkins University marked the fourth time daily deaths have exceeded 3,000 throughout the pandemic.”		1.5		–0.027
	Topic 54: concerns about vaccine scams that mine personal and financial details (important, information, warn, send, detail, info, scam, write, fall, and more)	“scam alert service has notified of a scam COVID-19 vaccine text linking to a bogus NHS website with a registration form for the vaccine in an attempt to mine personal and financial details.”		1.5		+0.141
	Topic 43: concerns about the safety of COVID-19 vaccines among pregnant women and children (should, woman, become, child, scientist, risk, man, decision, pregnant, and benefit)	“They have not experimented the COVID19 vaccine on pregnant women and young children.”		1.4		+0.078
	Topic 5: concerns about the reported statistics on adverse events of COVID-19 vaccine (report, reaction, cause, serious, severe, history, allergic, event, adverse, case)	“USA death rates: COVID-19 cases VS reported adverse events (CDC link) Specific rate: VACCINE MODERNA VACCINE FATALITY REPORT EVENT RATE: 5.82% COVID-19 CASE FATALITY RATE: 1.7%”		1.3		–0.243
	Topic 6: concerns about fitness to receive COVID-19 vaccines among individuals with medical conditions or allergies (know, read, jab, issue, need, have, people, rush, should, and article)	“Info so far, COVID19 vaccine is NOT a danger for people with allergies to foods or medications”		1.3		–0.004
	Topic 16: concerns about the short development phases of COVID-19 vaccines (flu, virus, cold, cure, common, different, cancer, sense, immunity, make)	“40 years research to find a cure for HIV AIDS.. still no vaccine. More than 100 years research to find a cure for cancer... still no vaccine. Ongoing research to find a cure for common cold and flu. Less than a year of Covid19 and you have a vaccine? No thanks! logicalthinking”		1.3		–0.060
	Topic 53: concerns that the vaccines would not be effective against a new strain of the COVID-19 virus (new, strain, post, case, virus, variant, will, mutate, lockdown, and year)	“New Strains Of COVID Could Render Vaccines Completely Useless, And 2 Dangerous New Strains Are Already Spreading via COVID19”		1.3		–0.029
	Topic 50: concerns about the short-term and long-term side effects of COVID-19 vaccines (effect, side, long, term, possible, potential, know, will, may, and short)	“COVID19 vaccines: What are the potential side effects? Doctors say most people will experience side effects such as fatigue, a sore arm for a day or two. Long-term effects are still unknow”		1.2		–0.023
	Topic 41: concerns about COVID-19 vaccines causing false positive results on HIV tests (test, positive, antibody, HIV, virus, testing, rapid, quarantine, symptom, and negative)	“This is completely false and misrepresented. The vaccines didn’t CAUSE people to get HIV, it caused them to have false-positive results. Totally different. Why an Australian COVID-19 vaccine caused false-positive HIV tests”		1.2		+0.147
Theme 3: discussions about news related to COVID-19 vaccines
	Topic 32: news about the launch of the COVID-19 vaccination drive in India (country, India, world, start, drive, will, nation, program, large, and poor)	“India is one of the world’s largest vaccine manufacturers. India has started one of the world’s largest mass vaccinations”		2.6		+0.133
	Topic 1: news about Oxford-AstraZeneca COVID-19 vaccine approval (UK, EU, roll, approve, AstraZeneca, Pfizer_, Britain, Oxford, country, and Europe)	“Cheapest Coronavirus Vaccine: UK Approves Oxford-AstraZeneca Jab, Rollout to Begin from Jan 4. OxfordAstraZeneca By far the cheapest vaccine.”		1.9		+0.139
	Topic 52: news about the effectiveness of the vaccines against new strains of the COVID-19 virus (new, may, variant, mutation, current, virus, spread, appear, find, and suggest)	“CNN: A new study provides early evidence that a Covid-19 vaccine might be effective against two new coronavirus variants first identified in South Africa and the UK, despite a concerning mutation.”		1.9		+0.074
	Topic 10: news about the approval of the Pfizer-BioNTech COVID-19 vaccine in the United States (use, Pfizer, approve, FDA, approval, authorization, Moderna, authorize, BioNTech, and seek)	“The FDA officially approves the Pfizer-Biontech coronavirus vaccine, the first approved in the U.S.”		1.7		+0.135
	Topic 13: news about progress in the development of various COVID-19 vaccines (trial, phase, show, result, datum, clinical, human, study, candidate, and efficacy)	“still in phase 3 clinical trials. There are now about 12 COVID-19 vaccines in phase-3, only Pfizer, Moderna and Gamaleya have released interim efficacy results. Even AstraZeneca which was one of the first to enter phase-3 have not released efficacy results.”		1.7		+0.150
	Topic 25: news about the approval of the Moderna COVID-19 vaccine in the United States (recommend, clear, US, FDA, vote, meet, panel, business, Moderna, and CEO)	“US clears second vaccine by Moderna for COVID-19: US clears Moderna vaccine for COVID-19”		1.2		+0.155
	Topic 23: news about the approval of the Pfizer-BioNTech COVID-19 vaccine outside of the United States (emergency, BioNTech, Pfizer, approve, drug, UK, Moderna, could, worry, and the_United_States)	“Canada also approves COVID19Vaccine. Health Canada officially approves the Pfizer-BioNTech COVID-19 vaccine”		1.1		+0.126
	Topic 56: news about the impact of COVID-19 around the world (doctor, NHS, policy, health, today, insurance, retweet, biotech, patients, and todaysmedicalupdate)	“As the virus resurges, mental health woes batter France”		0.8		+0.198
	Topic 35: general news related to COVID-19 (medicine, pharmaceutical, medtech, politic, industry, breakingnews, FoxNews, health, giant, and science)	“California Reports First Case Of New COVID Variant”		0.5		+0.065
Theme 4: public health communications about COVID-19 vaccines
	Topic 8: involving an expert panel in public education on COVID-19 vaccines (expert, answer, join, discuss, Dr, concern, regard, key, check, and address)	“On this special episode, we talk with Dr. Steve Rockoff from Henry Ford West Bloomfield and Dr. Russell Faust from Oakland County Health as they answer FAQs about the COVID19 vaccine”		1.6		+0.258
	Topic 9: using radio as a medium to clarify questions related to COVID-19 vaccines (question, ask, lot, wonder, talk, take, will, listen, hear, and come)	“Have a question about Covid or the vaccine? Send them my way and I'll ask as many as I can to our experts on-air!”		1.6		+0.139
	Topic 22: using video to explain how COVID-19 vaccines work (patient, video, staff, watch, check, fact, live, link, email, message)	“Loved youtube videos on the Covid-19 vaccine! For those who are unsure and want to learn about how the covid-19 vaccine works please watch the video below!”		1.5		+0.213
	Topic 34: summarizing the evidence on the efficacy of the Johnson & Johnson vaccine (effective, safe, prevent, disease, infection, show, single, Johnson, severe, and say)	“BREAKING: Johnson & Johnson says its single-shot covid-19 vaccine is: - 66% effective against moderate disease - 85% effective against severe disease”		1.5		+0.276
	Topic 51: summarizing the evidence for the efficacy of the Sinovac vaccine (China, develop, produce, buy, Russia, Chinese, AstraZeneca, deal, Brazil, and purchase)	“An experimental COVID-19 vaccine developed by Chinese biopharmaceutical company Sinovac is 91.25% effective, a Turkish health official said on Thursday.”		1.5		+0.094
	Topic 7: providing simple explanations on how COVID-19 vaccines can help in achieving herd immunity (life, will, save, change, immunity, stop, end, cost, herd, and affect)	“The vast majority of vaccinated people will be protected from contracting Covid-19 at all. In turn, the virus will have far fewer opportunities to spread through the population (think a forest that’s 90% firebreaks) and so transmission will be massively reduced.”		1.3		+0.115
	Topic 20: providing simple explanations about how mRNA vaccines work (system, immune, virus, body, make, future, will, DNA, cell, mind)	“The vaccine will not contain any virus. It will only contain the instructions (mRNA) on how to build those spike proteins. Your body then learns how to recognize those spikes so that your immune system can kill coronavirus.”		1.3		+0.104
Theme 5: discussions about the approach to COVID-19 vaccination drives
	Topic 14: involving public figures to gain public trust regarding COVID-19 vaccines (take, say, public, available, trust, refuse, people, Americans, and would)	“I trust it and will take the vaccine when available! Obama, Bush and Clinton say they will take the COVID-19 vaccine publicly to gain public trust”		3.2		+0.154
	Topic 48: using an appointment system to register for COVID-19 vaccination (appointment, call, sign, make, old, schedule, clinic, eligible, senior, and register)	“Florida has launched a statewide pre-registration system for individuals who are eligible for the COVID-19 vaccine. You can pre-register for appointments and be notified when appointments are available in your area by visiting”		2.5		+0.100
	Topic 24: involving employers to facilitate COVID-19 vaccination (can, wait, require, travel, make, employee, return, employer, mandate, and proof)	“Companies are considering compulsory COVID19 vaccination as a condition of employment. ‛Under the law, an employer can force an employee to get vaccinated, and if they don’t, fire them,’ said Rogge Dunn, a Dallas labor and employment attorney.”		2.1		+0.076
	Topic 45: clarifying the subpopulations to prioritize for COVID-19 vaccines (care, health, school, home, teacher, worker, access, risk, include, and staff)	“When the vaccine is rolled out and the elderly especially in long term care and all health care workers are vaccinated, teachers should be soon after. If face to face brick and mortar schools are considered essential, teachers, education workers and school staff must be soon after.”		1.8		+0.153
	Topic 28: providing COVID-19 vaccines to frontline workers (worker, line, healthcare, frontline, front, next, essential, cut, stand, and place)	“COVID19 vaccine now for all frontline healthcare workers - patient care workers, no matter their title, deserve it before administrators.”		1.7		+0.103
	Topic 4: prioritizing COVID-19 vaccines for long-term care homes (health, care, home, facility, will, resident, roll, worker, official, and minister)	“The Province will begin COVID-19 vaccinations of health-care and long-term care workers at hospitals in Toronto and Ottawa starting Dec. 15”		1.6		+0.209
	Topic 46: defining high-risk health conditions to prioritize for COVID-19 vaccines (group, free, priority, list, pay, should, people, citizen, general, and give)	“Should smoking be considered a high risk condition and smokers have priority for CovidVaccine?”		1.5		+0.109
	Topic 36: addressing mistrust among minority communities with regard to COVID-19 vaccination (community, challenge, leader, fear, black, role, hesitancy, equity, approach, and market)	“As MDs, it is crucial that we discuss this sensitive issue among our vulnerable minority communities, esp because it has/is still annihilating Black/Latinx communities. We must first acknowledge the history of medical mistrust.”		1.4		+0.210
	Topic 58: showing COVID-19 vaccination of public figures on live television (president, live, receive, nurse, Dr, Biden, watch, elect, Joe_Biden, and former)	“US president-elect Joe Biden receives Pfizer’s Covid-19 vaccine shot on live television”		1.4		+0.144
Theme 6: discussions about the distribution of COVID-19 vaccines
	Topic 27: updates on the number of people who have received COVID-19 vaccines (dose, say, receive, Pfizer, administer, people, arrive, accord, distribute, and first)	“To date, 7,761 doses of the COVID-19 vaccine have been administered in Connecticut. Last week, we received 31,200 doses of Pfizer’s vaccine and anticipate receiving another 24,375 of that vaccine this week.”		2.7		+0.096
	Topic 15: call for equitable access to COVID-19 vaccines across different countries (need, help, protect, ensure, work, must, bring, can, let, and access)	“No one is safe until everyone is safe COVAX: Ensuring global equitable access to COVID-19 vaccines”		2.1		+0.297
	Topic 38: discussions about the distribution plan of COVID-19 vaccines in the United States (Trump, company, administration, speed, development, delivery, promise, distribution, effort, and US)	“The federal ‛Operation Warp Speed’ calls on multiple organizations and companies in the logistics of distributing of millions of COVID-19 vaccines.”		2.0		+0.062
	Topic 57: call for a coordinated distribution plan of COVID-19 vaccines (plan, distribution, Biden, pandemic, strategy, rollout, national, release, relief, and economic)	“Decentralization of the distribution of vaccine has left a patchwork of madness. Vaccine distribution must be a National plan with the distribution centralized with the military. This is war - fight Covid like a war.”		2.0		+0.096
	Topic 47: comparing the statistics related to COVID-19 and COVID-19 vaccination in the United States (state, number, rate, governor, track, California, slow, rollout, total, and case)	“Maryland coronavirus cases 1/18 328,214 0.5% higher than day before (+1769) Deaths 6423 0.45% higher than day before (+29) Hospitalizations day over day ICU +13 (421) Acute +14 (1429) Vaccines day over day +9569 (233,309)”		1.8		+0.023
	Topic 49: updates on the shipment of COVID-19 vaccines (dose, hospital, expect, begin, shipment, Pfizer, will, arrive, breaking, and batch)	“UPS and FedEx trucks carrying the first U.S. shipment of coronavirus vaccine have left Pfizer’s facility near Kalamazoo, Michigan.”		1.7		+0.056
	Topic 21: call for equitable access to COVID-19 vaccines across different income groups (would, could, Trump, like, god, time, election, American, money, and America)	“The Elite & Wealthy truly SUCK! The wealthy scramble for COVID-19 vaccines: ‛If I donate $25,000 ... would that help me?’ Vaccine Sad Wealthy covid CovidVaccine COVID19”		1.6		+0.153
	Topic 44: updates on the rollout of the COVID-19 vaccination plan in Canada (Canada, government, will, force, minister, cdnpoli [Canadian politics], say, Ontario, head, and restriction)	“The Canadian military says it will be ready to distribute COVID-19 vaccines At noon, federal officials are providing an update on Canada’s vaccination plan”		1.6		+0.039
	Topic 39: call for equitable access to COVID-19 vaccines across different ethnic groups (population, world, lead, Israel, provide, race, corona, power)	“Human Rights Watch has called on ‛Israel’ to provide COVID-19 vaccines to more than 4.5 million Palestinians in the occupied West Bank and Gaza Strip. HRW urges ‛Israel’ to provide COVID vaccines to Palestinians”		1.5		+0.035
	Topic 29: updates on the rollout of COVID-19 vaccination sites (site, open, mass, testing, close, centre, major, city, injection, and turn)	“Mass vaccination sites soon will be added to Chicago’s mass testing sites COVID19”		1.4		+0.075
	Topic 3: guidelines on the ethical considerations in the allocation of COVID-19 vaccines (follow, CDC [Centers for Disease Control and Prevention], meeting, director, guidance, guideline, recommendation, publichealth, allocation, and update)	“In addition to scientific data and implementation feasibility, four ethical principles will assist ACIP in formulating recommendations for the initial allocation of COVID-19 vaccine: 1) maximizing benefits and minimizing harms; 2) promoting justice;”		1.0		+0.107
	Topic 2: comparing the statistics related to COVID-19 and COVID-19 vaccination outside of the United States (high, low, economy, reduce, contract, risk, price, mortality, and pandemic)	“Italy seems close to rise again in its COVID19 epidemic activity (R-eff=1.07), at high levels of activity, plateauing at very high levels of mortality, for 7 more days. 128,880 vaccinated as of Jan 04.”		0.9		+0.042

^aThe sentiment scores range from –1 (most negative sentiment) to +1 (most positive sentiment).