Updated June 1, 2021.

Comirnaty BNT162b2/Pfizer (US) & BioNTech (Germany) mRNA-1273/ Moderna (US) Ad26.COV2.S/Johnson & Johnson (aka Janssen) (US) Vaxzevria AZD1222/Oxford (UK) & AstraZeneca (UK-Sweden) Sputnik V (Russia) Sinopharm/ BBIBP-CorV (China)
Technology
mRNA mRNA DNA in adenoviral vector DNA in adenoviral vector DNA in 2 adenoviral vectors Inactivated coronavirus (SARS-CoV-2 strain)
Where authorized
US and 79 other countries US and 50 other countries US and 41 other countries 103 countries, but not US 68 countries, but not US 43 countries, but not US
Number of injections
2 doses, 3 weeks apart. 2 doses, 4 weeks apart. 1 dose. 2 doses, 4 weeks apart. First dose with rAD26 adenovirus, second dose with rAd5 adenovirus, 3 weeks apart. Russia has authorized for export a less expensive one-injection “Sputnik Light” vaccine with 79.4% efficacy (26). 2 doses, 3 to 4 weeks apart.
Storage conditions
Up to 1 month undiluted at 36–46°F (33). Up to 30 days with refrigeration. Up to 3 months at 36–46°F. 6+ months with refrigeration. Stored at 0°F for trial; approved for storage at 36-46° F. Should be stored and transported at 36°–46°F.
Doses administered in US, as of May 23
159 million 125 million 11 million 0 (not authorized in US) 0 (not authorized in US) 0 (not authorized in US)
Estimated efficacy vs. symptomatic COVID-19 infection
95% 7+ days after 2nd dose in clinical trial (1); 97.0% effective in real-world study in Israel (28). 94.1% 14+ days after second dose in clinical trial (10). 72% in US, 64% in South Africa, 61% in South America 28+ days after vaccination in clinical trial (14). 76.7% efficacy in real-world study in US (34). 76% in latest clinical trial in US, Peru and Chile, which tested standardized dosages administered four weeks apart. In earlier trials, the dosages and the intervals between injections were inconsistent (18). 91.6% at day 21 after first dose in clinical trial (25). 97.6% efficacy 35+ days after first injection in real-world study in Russia (27). 78.1% in clinical trial (31).
Estimated efficacy vs. severe COVID-19 infection
90% in clinical trial (1); 94% effective vs. COVID-19 hospitalization in adults 65+ in real-world study in US (30). 100% 14+ days after 2nd dose in clinical trial (10); 94% effective vs COVID-19 hospitalization in adults 65+in real-world study in US (30). 85.9% in US, 87.6% in Brazil, and 81.7% in South Africa at 28+ days post-vaccination in clinical trial (14). 100% in latest clinical trial (18). 100% 21+ days after first dose in clinical trial (25). Too few severe cases in clinical trial for an estimate (31).
Estimated efficacy vs. asymptomatic COVID-19 infection
80% in real-world study of those who received either Pfizer-BioNTech or Moderna vaccines in US (3). 91.5% effective in real-world study in Israel (28). 80% in real-world study of those who received either Pfizer-BioNTech or Moderna vaccines in US (3). Data too limited in clinical trial (14). No data available from latest clinical trial. Not measured in clinical trial. No data from clinical trial.
Estimated efficacy in older adults
93.7% in ages 55+ at 7+ days after 2nd dose in clinical trial (1); 96.4% effective vs symptomatic COVID-19 infection in adults 65+ in real-world study in Israel (28). 86.4% in ages 65+ at 14+ days after 2nd dose in clinical trial (10). 66.2% in ages 60+ overall in US, South Africa, and Brazil 28+ days after vaccination in clinical trial (14). 85% in ages 65+ in latest clinical trial (18). 91.8% in ages 60+ 21 days after first dose in clinical trial (25). Too few older adults in clinical trial for an estimate (31).
Efficacy against Alpha (United Kingdom) variant (B.1.1.7)
86% efficacy in real-world study in UK (where dominant variant was B.1.1.7.) (4). 89.5% efficacy in real-world study in Qatar (29). Significant immune response based on in vitro tests (11). No data. 74.6% in UK clinical trial (19). Not reported. Significant immune response based on in vitro tests (32).
Efficacy against Beta (South Africa) variant (B.1.351)
Reduced, but still significant immune response based on in vitro tests (5,6). 75.0% efficacy in real-world study in Qatar (29). Reduced, but still significant immune response based on in vitro tests (11). 64% vs. moderate to severe/critical and 81.7% vs severe/critical COVID-19 infections 28+ days after vaccination in South Africa (where this variant accounted for nearly all COVID-19 cases) (14). 10.4% in clinical trial in South Africa (20). Not reported. Reduced, but still significant immune response based on in vitro tests (32).
Efficacy against Gamma (Brazil) variant (P.1/P.2)
Significant immune response based on in vitro tests (6). Reduced, but still significant immune response based on in vitro tests (11). 68.1% vs. moderate to severe/critical and 87.6% vs. severe/critical infections 28+ days after vaccination in clinical trial in Brazil (where there was high prevalence of P.2.) (14). Significant immune response based on in vitro tests (21). Not reported No data.
Efficacy against Delta (India) variants (B.1.617.1/B.1.617.2)
Reduced, but still significant immune response vs B.1.617.1 based on in vitro tests (35); 87.9% efficacy vs B.1.617.2 in real-world study in England (36). Reduced, but still significant immune response vs B.1.617.1 based on in vitro tests (35). No data. 59.8% efficacy vs B.1.617.2 in real-world study in England (37). No data. No data.
Data published
Yes (1). Yes (10). Submitted to FDA (14). Press release (18). Interim results after first dose in clinical trial (25). No.
Notable safety concerns
Most common adverse reactions in clinical trial were fatigue and headache, which were severe enough after the 2nd dose to prevent daily activity in less than 4% of recipients (1). About 1 in 6 recipients reported adverse reactions after 2nd dose in clinical trial, especially fatigue or muscle pain, severe enough to prevent daily activity (10). Adverse reactions severe enough to prevent daily activity in 1% of recipients. FDA reviewed 15 cases of rare, severe blood clots, mostly in women 18-59, and concluded the vaccine's benefits outweigh the risks. (14, 15). Vaccine recipients did not report serious adverse reactions more often than placebo recipients. Mild to moderate reactions included soreness, headache, fatigue, muscle pain. Rare blood clotting disorder listed as a very rare side effect (22, 23). Most common adverse reactions in clinical trials were flu-like illness, injection-site reactions, headache, and asthenia (fatigue). Vaccine recipients did not report serious adverse events more frequently than placebo recipients (10). The most common adverse reactions in the clinical trial were mild to moderate injection-site pain, headache and fatigue. Less than 1% of the adverse reactions were severe (31).
Risk of anaphylaxis
Rare; 11.1 cases per one million doses recorded during a week of monitoring in December (7). Rare; 2.5 cases per one million doses recorded during 3 weeks of monitoring in December-January (12). None reported in trial. 1 case in 15,000+ participants in trials. No cases reported among 12,296 participants in clinical trial (25). No cases reported among 14,338 vaccine recipients in clinical trial (31).
Minimum age authorized
12+; 100% efficacy in clinical trial of 12- to 15-year-olds (8). 18+; Company reported that in a clinical trial of 12- to 17-year-olds their immune response was comparable to immune response of adults given the vaccine and plans to seek Emergency Use Authorization from FDA for this age group (13). 18+; company has a Phase 2 clinical trial underway that includes 12- to 17-year-olds (16). Clinical trial tested 18+; company has a clinical trial underway in 6- to 17-year-olds (24). Clinical trial tested 18+; no trials yet in children. 18+.
Safety for pregnant women
Clinical trial in pregnant women initiated in February 2021 (9). Preliminary real-world findings from Dec 2020 through Feb 2021 did not show obvious safety concerns among pregnant women who received the vaccine (38). Company maintains registry monitoring pregnancy outcomes in women vaccinated during pregnancy. Preliminary real-world findings from Dec 2020 through Feb 2021 did not show obvious safety concerns among pregnant women who received the vaccine (38). No data. Outcomes for all reported pregnancies in clinical trial participants being collected; company has a Phase 2 clinical trial planned in pregnant women (17). No data. Pregnant women excluded from trials. No data. Pregnant women excluded from trials. No data. Pregnant women excluded from trial.

[1] Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine (December 10, 2020)
Supplemental information
[2] BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Mass Vaccination Setting (February 24, 2021)
[3] Impact of the COVID-19 Vaccine on Asymptomatic Infection Among Patients Undergoing Pre-Procedural COVID-19 Molecular Screening (March 10, 2021)
[4] Effectiveness of BNT162b2 mRNA Vaccine Against Infection and COVID-19 Vaccine Coverage in Healthcare Workers in England, Multicentre Prospective Cohort Study
[5] Neutralization of viruses with European, South African, and U.S. SARS-CoV-2 variant spike proteins by convalescent sera and BNT162b2 mRNA vaccine-elicited antibodies
(February 7, 2021)
[6] In vitro activity Neutralizing Activity of BNT162b2-Elicited Serum (March 8, 2021)
[7] Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Pfizer-BioNTech COVID-19 Vaccine — United States, December 14–23, 2020 (January 6, 2021)
[8] FDA Authorizes Pfizer-BioNTech COVID-19 Vaccine for Emergency Use in Adolescents
(May 10, 2021)
[9] Pfizer and BioNTech Commence Global Clinical Trial to Evaluate COVID-19 Vaccine in Pregnant Women
(February 18, 2021)
[10] Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine (December 30, 2020)
Supplemental information
[11] Serum Neutralizing Activity Elicited by mRNA-1273 Vaccine (March 17)
[12] Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Moderna COVID-19 Vaccine — United States, December 21, 2020–January 10, 2021
(January 22, 2021)
[13] Moderna Announces TeenCOVE Study of its COVID-19 Vaccine in Adolescents Meets Primary Endpoint and Plans to Submit Data to Regulators in Early June (May 25, 2021)
[14] FDA Briefing Document: Janssen Ad26.COV2.S Vaccine for the Prevention of COVID-19
(February 26, 2021)
[15] FDA News Release: FDA and CDC Lift Recommended Pause on Johnson & Johnson (Janssen) COVID-19 Vaccine Use Following Thorough Safety Review
(April 23, 2021)
[16] Johnson & Johnson Expands Phase 2a Clinical Trial of COVID-19 Vaccine Candidate to Include Adolescents (April 2, 2021)
[17] A Study of Ad26.COV2.S in Healthy Pregnant Participants (COVID-19) (HORIZON 1) (February 21, 2021)
[18]
AZD1222 US Phase III primary analysis confirms safety and efficacy
(March 25, 2021)
[19] Efficacy of ChAdOx1 nCoV-19 (AZD1222) Vaccine Against SARS-CoV-2 VOC 202012/01 (B.1.1.7) (February 4, 2021)
[20] Safety and efficacy of the ChAdOx1 nCoV-19 (AZD1222) Covid-19 vaccine against the B.1.351 variant in South Africa
(February 12, 2021)
[21] Antibody evasion by the Brazilian P.1 strain of SARS-CoV-2 (March 15, 2021)
[22] AstraZeneca’s COVID-19 vaccine: EMA finds possible link to very rare cases of unusual blood clots with low blood platelets (April 7, 2021)
[23] Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK
(December 8, 2020)
[24] Oxford University extends COVID-19 vaccine study to children (February 12, 2021)
[25] Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: an interim analysis of a randomised controlled phase 3 trial in Russia. (February 2, 2021)
[26] Russia authorises single-dose Sputnik Light COVID vaccine for use -RDIF (May 6, 2021)
[27] Russia's Sputnik V vaccine 97.6% effective in real-world study (April 19, 2021)
[28] Impact and effectiveness of mRNA BNT162b2 vaccine against SARS-CoV-2 infections and COVID-19 cases, hospitalisations, and deaths following a nationwide vaccination campaign in Israel (May 5, 2021)
[29] Effectiveness of the BNT162b2 Covid-19 Vaccine against the B.1.1.7 and B.1.351 Variants (May 5, 2021)
[30] Effectiveness of Pfizer-BioNTech and Moderna Vaccines Against COVID-19 Among Hospitalized Adults Aged ≥65 Years — United States, January–March 2021 (May 7, 2021)
[31] World Health Organization Background document on the inactivated COVID-19 vaccine BIBP developed by China National Biotec Group (CNBG), Sinopharm (May 7, 2021)
[32] Susceptibility of Circulating SARS-CoV-2 Variants to Neutralization (April 6, 2021)
[33] FDA Authorizes Longer Time for Refrigerator Storage of Thawed Pfizer-BioNTech COVID-19 Vaccine Prior to Dilution, Making Vaccine More Widely Available (May 19, 2021)
[34] Real-world effectiveness of Ad26.COV2.S adenoviral vector vaccine for COVID-19 (April 30, 2021)
[35] Infection and vaccine-induced neutralizing antibody responses to the SARS-CoV-2 B.1.617.1 variant (May 10, 2021)
[36] Effectiveness of COVID-19 vaccines against the B.1.617.2 variant (May 19, 2021)
[37] Effectiveness of COVID-19 vaccines against the B.1.617.2 variant (May 19, 2021)
[38] Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons. (April 21, 2021)

Our Methods

These five vaccines were chosen because their trial results have been published in detail and they have been authorized for use in the United States or in other countries.

Sources of general information about the vaccines, such as their technology, storage conditions, and number of administered doses, are the New York Times Vaccine Tracker and the Centers for Disease Control and Prevention (CDC).

Sources of information about the efficacy and safety of the vaccines are the published clinical trials themselves, U.S. Food and Drug Administration (FDA) documents, and a company announcement from AstraZeneca about the results of its latest trial in the United States.

Sources of information about planned or in-progress vaccine trials are clinicaltrials.gov, company announcements, and news reports such as The Medical Letter.

This website will be updated on a weekly basis.