. 2021 May 7;70(18):680–684. doi: 10.15585/mmwr.mm7018e2
David K Shay
1,✉, Julianne Gee
1, John R Su
1, Tanya R Myers
1, Paige Marquez
1, Ruiling Liu
1, Bicheng Zhang
1, Charles Licata
1, Thomas A Clark
1, Tom T Shimabukuro
1
PMCID: PMC9368748PMID: 33956784
On February 27, 2021, the Food and Drug Administration (FDA) issued an Emergency UseAuthorization (EUA) for Janssen (Ad.26.COV2.S) COVID-19 vaccine (Janssen Biotech, Inc.,a Janssen Pharmaceutical company, Johnson & Johnson) (1). The Janssen COVID-19 vaccine, the third COVID-19vaccine authorized for use in the United States, uses a replication-incompetent humanadenoviral type 26 vector platform* (2) and is administered as a singleintramuscular dose, whereas the first two authorized vaccines use an mRNA platform andrequire 2 doses. On February 28, 2021, the Advisory Committee on Immunization Practices(ACIP) issued interim recommendations for use of Janssen COVID-19 vaccine among personsaged ≥18 years (3). DuringApril 13–23, CDC and FDA recommended a pause in use of Janssen vaccine afterreports of six cases of cerebral venous sinus thrombosis (CVST) with thrombocytopenia(platelet count <150,000/μL of blood) among Janssen vaccinerecipients (4). Similarthrombotic events, primarily among women aged <60 years, have been described inEurope after receipt of the AstraZeneca COVID-19 vaccine, which uses areplication-incompetent chimpanzee adenoviral vector (5–7). The U.S. CVST cases that prompted the pause inJanssen vaccination, as well as subsequently detected CVST cases, are describedelsewhere (8). This reportsummarizes adverse events among Janssen vaccine recipients, including non-CVST cases ofthrombosis with thrombocytopenia syndrome (TTS), reported to the Vaccine Adverse EventsReporting System (VAERS), a passive surveillance system, and through v-safe, an activemonitoring system. As of April 21, 2021, 7.98 million doses of the Janssen COVID-19vaccine had been administered. Among 13,725 VAERS reports reviewed, 97% were classifiedas nonserious and 3% as serious,†including three reports among women of cases of thrombosis in large arteries or veinsaccompanied by thrombocytopenia during the second week after vaccination. These threecases and the previously detected CVST cases are consistent with 17 cases of TTS,§ a newly defined condition.Approximately 338,700 Janssen COVID-19 vaccine recipients completed at least one v-safesurvey during the week after vaccination; 76% reported a systemic reaction, 61% reporteda local reaction, and 34% reported a health impact.¶ Fatigue and pain were commonly reported symptoms inboth VAERS and v-safe. The overall safety profile is consistent with preauthorizationclinical trials data. Prompt review of U.S. vaccine safety data detected threeadditional cases of non-CVST TTS, in addition to the previously recognized CVST casesthat initiated the pause in use of the Janssen COVID-19 vaccine. Ongoing monitoring ofadverse events after COVID-19 vaccination, including vaccination with the Janssensingle-dose vaccine, is essential for evaluating the risks and benefits of eachvaccine.
VAERS is a national passive surveillance program managed by CDC and FDA that monitorsadverse events after all vaccinations (9). VAERS reports are accepted from health care providers,vaccine manufacturers, and the public. Under EUAs for each COVID-19 vaccine, health careproviders are required to report several types of adverse events to VAERS, including alldeaths.** Signs and symptoms in VAERS reportsare coded using the Medical Dictionary for Regulatory Activities (MedDRA).†† VAERS staff membersattempt to obtain medical records and supporting information from health care providersfor all reported serious events, as well as death certificates and autopsy reports forall deaths.
V-safe is a new, voluntary text-based surveillance system designed to collect additionalinformation about COVID-19 vaccine adverse events, particularly for common sideeffects.§§ Vaccinerecipients who enroll in v-safe receive regularly scheduled text message reminders tocomplete short online health surveys that include questions about local injection siteand systemic reactions and health impacts (i.e., whether the enrollee was unable toperform normal daily activities, missed work, or received care from a medicalprofessional because of new symptoms or conditions).¶¶ Enrollees who report seeking medical careare contacted by CDC’s v-safe call center and encouraged to complete a VAERSreport, if indicated.
In this report, VAERS and v-safe data are described by sex, age group, and race/ethnicityof vaccine recipients. VAERS data include reports received and processed during March2–April 21. V-safe data from persons vaccinated during March 2–April 12were analyzed to permit time for respondents to complete up to eight daily healthsurveys after vaccination. These activities were reviewed by CDC and are consistent withapplicable federal law and CDC policy.***
As of April 21, 2021, 7.98 million doses of Janssen COVID-19 vaccine had beenadministered in the United States, 50% to women. The median age at vaccination was 50years. Race/ethnicity was unknown for 39% of persons vaccinated; 38% were non-HispanicWhite (White).
Review of VAERS Data
VAERS received and processed††† 13,725 adverse event reports forJanssen COVID-19 vaccine recipients; median age was 42 years, and 66% were women(Table 1). Among these VAERS reports,13,294 (97%) were classified as nonserious, and 343 (3%) were classified as serious,including three reports of non-CVST TTS (no deaths). Two of the TTS cases occurredamong women aged 30–39 years and one in a woman aged 50–59 years. Eachof these women had evidence of large-vessel thrombosis and thrombocytopenia (Table 2). As of April 25, 14 CVST cases hadbeen confirmed (8), for atotal of 17 TTS cases.
TABLE 1. Percentage of nonserious and serious adverse events after receipt ofJanssen COVID-19 vaccine, by demographic characteristics of vaccinerecipients and reported symptoms — Vaccine Adverse Event ReportingSystem, United States, March–April 2021.
| Characteristic | Total (N = 13,725) | Severityof adverse event, %* | ||
|---|---|---|---|---|
| Nonserious (n = 13,294) | Serious, excludingdeath (n = 343) | Death (n =88) | ||
| Sex | ||||
| Female | 66.2 | 66.6 | 57.1 | 50.0 |
| Male | 31.2 | 30.8 | 40.5 | 43.2 |
| Unknown | 2.6 | 2.6 | 2.3 | 6.8 |
| Age group,yrs | ||||
| 0–17 | 1.5 | 1.6 | 0.6 | 0.0 |
| 18–49 | 57.0 | 57.9 | 34.4 | 13.6 |
| 50–64 | 26.8 | 26.7 | 33.8 | 18.2 |
| 65–74 | 6.8 | 6.5 | 14.3 | 18.2 |
| 75–84 | 1.8 | 1.5 | 6.4 | 15.9 |
| ≥85 | 0.6 | 0.4 | 3.2 | 19.3 |
| Unknown | 5.6 | 5.5 | 7.3 | 14.8 |
| Race/Ethnicity | ||||
| Hispanic or Latino | 7.3 | 7.3 | 6.1 | 1.1 |
| Non-Hispanic orLatino | ||||
| American Indian or Alaska Native | 0.2 | 0.2 | 0.0 | 0.0 |
| Asian | 2.3 | 2.3 | 1.5 | 3.4 |
| Black | 3.4 | 3.3 | 5.5 | 8.0 |
| NativeHawaiian or Pacific Islander | 0.1 | 0.1 | 0.0 | 0.0 |
| White | 58.4 | 58.6 | 52.2 | 45.5 |
| Multiracial | 1.3 | 1.3 | 0.9 | 0.0 |
| Other | 0.4 | 0.4 | 0.3 | 1.1 |
| Unknown race | 0.5 | 0.5 | 1.5 | 2.3 |
| Unknownethnicity | ||||
| American Indian or Alaska Native | 0.1 | 0.1 | 0.0 | 0.0 |
| Asian | 0.3 | 0.3 | 0.6 | 2.3 |
| Black | 0.8 | 0.7 | 2.6 | 1.1 |
| NativeHawaiian or Pacific Islander | <0.1 | <0.1 | 0.0 | 0.0 |
| White | 5.8 | 5.7 | 8.8 | 9.1 |
| Multiracial | 0.2 | 0.2 | 0.0 | 0.0 |
| Other | 1.7 | 1.7 | 0.9 | 0.0 |
| Unknownrace/ethnicity | 17.4 | 17.3 | 19.2 | 26.1 |
| Reportedsymptoms | ||||
| Headache | 34.4 | 35.0 | 17.8 | 6.8 |
| Fever | 33.7 | 34.2 | 21.6 | 8.0 |
| Chills | 32.7 | 33.3 | 14.9 | 4.6 |
| Pain | 25.5 | 26.1 | 10.2 | 1.1 |
| Fatigue | 23.9 | 24.3 | 12.8 | 5.7 |
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* Reports are classified as serious if any of the following are reported:death, life-threatening illness, hospitalization or prolongation ofhospitalization, permanent disability, congenital anomaly, or birthdefect.
TABLE 2. Characteristics of patients with evidence of thrombosis withthrombocytopenia syndrome* afterreceipt of Janssen COVID-19 vaccine — Vaccine Adverse EventsReporting System, United States, March–April, 2021.
| Patient | Age group, yrs | Days to symptom onset aftervaccination | Initial signs andsymptoms | Later signs andsymptoms | Lowest plateletcount† | Anti-PF4 antibodystatus§ | Location ofthrombus/occlusion |
|---|---|---|---|---|---|---|---|
| A | 30–39 | 10 | Headache, left-sidedparesis | Headache, left-sidedparesis | 60,000/μL | Positive | Right carotid artery, left brachial vein,right femoral vein |
| B | 50–59 | 11 | Left legswelling, bruising | Bilateral lower extremityswelling | 15,000/μL | Not available | Left lower extremity deep vein, rightfemoral artery, left and right iliac arteries |
| C | 30–39 | 6 | Nausea, vomiting, shortnessof breath, altered mental status | Nausea, vomiting, shortnessof breath, altered mental status | 20,000/μL | Not available | Portal vein, superior mesenteric andsplenic arteries, pulmonary artery |
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Abbreviations: PF4 = platelet factor 4; TTS = thrombosis withthrombocytopenia syndrome.
* Patients with evidence of TTS not classified as cerebral venous sinusthrombosis. Brighton Collaboration’s draft interim case findingdefinition for TTS: any patient presenting with acute venous or arterialthrombosis and new onset thrombocytopenia, with no known exposure to heparinor any other underlying condition or explanation for the condition.https://brightoncollaboration.us/wp-content/uploads/2021/04/TTS-Case-Finding-and-Definition-Process.v1.0-1-1.pdf
† Normalrange=150,000–450,000/μL.
§ The heparin:PF4 complex is the antigen in heparin-inducedthrombocytopenia, an autoimmune reaction to administration of heparin, ananticoagulant. Anti-PF4 antibodies also have been found in patients withthrombosis who have no known exposure to heparin. Anti-PF4 antibodies havebeen detected in persons with thrombosis and thrombocytopenia after receiptof Janssen and AstraZeneca COVID-19 vaccines (Scully M, Singh D, Lown R, etal. Pathologic antibodies to platelet factor 4 after ChAdOx1 nCoV-19vaccination. N Engl J Med 2021. Epub April 16, 2021).
CDC and FDA reviewed 88 reports of death after receipt of Janssen COVID-19 vaccine;death certificates were available for 12 (14%). Among the 88 reported decedents, 44were female, 38 were male, and the sex of six was not reported (Table 1). The median decedent age was 69 years(range=21–97 years); median interval from vaccination todeath was 2 days (range=0–23 days). All death reportsreceived a medical review§§§; the most frequent preliminaryimpressions of CDC and FDA reviewers regarding cause of death were 1) decedent founddead, with no additional details available (34 reports); 2) cardiac arrest orcardiovascular disease (23 reports); 3) COVID-19 disease (eight reports); and 4)cerebrovascular disease (five reports). As of most recent follow-up (April 28,2021), three patients with TTS had died. Among 79 reports of anaphylaxis aftervaccination, four were confirmed as anaphylaxis cases after interview with a healthcare provider or review of medical records (<0.5 cases per 1 million dosesadministered); four reports remain under review. Headache (34%), fever (34%), chills(33%), injection site pain (26%), and fatigue (24%) were the symptoms mostfrequently reported to VAERS (Table 1).
Review of v-safe Data
During March 2–April 12, v-safe enrolled 338,765 Janssen COVID-19 vaccinerecipients who completed at least one postvaccination survey. The median age ofv-safe enrollees was 46 years (range=15–109 years); 60% werewomen (Supplementary Table, https://stacks.cdc.gov/view/cdc/105473). Sixty-seven percent ofenrollees identified as White. During days 0–7 after vaccination, 76% ofenrollees reported at least one systemic reaction, and 61% reported at least oneinjection site reaction (Table 3). Fatigue,pain, and headache were the most commonly reported reactions. Symptoms were mostfrequently reported on the first day after vaccination; the proportion of enrolleesreporting specific reactions decreased with number of days since vaccination. Onpostvaccination day 1, 28% of enrollees reported being unable to perform normal,daily activities, and 16% reported being unable to work. Only 1.4% of enrolleesreported seeking any form of medical care in the 7 days after vaccination.
TABLE 3. V-safe enrollees who completed at least one survey and reported a localor systemic reaction or health impact on days 0–7 after receivingJanssen COVID-19 vaccine — United States, March 2–April 12,2021.
| Event | Percentage of enrollees reporting reaction or healthimpact | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Days0–7* | Day 0 | Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 | |
| Totalenrollees, no. (%) of enrolleesreporting† | 338,765 (100) | 207,483 (61) | 259,535 (77) | 261,096 (77) | 251,676 (74) | 238,946 (71) | 225,427 (67) | 209,958 (62) | 202,138 (60) |
| Reactionreported | |||||||||
| Fatigue | 59.1 | 17.9 | 56.3 | 26.2 | 16.7 | 12.8 | 11.0 | 9.8 | 9.0 |
| Injection site pain | 57.9 | 31.6 | 48.5 | 39.1 | 30.1 | 21.5 | 13.7 | 7.9 | 5.0 |
| Headache | 52.2 | 13.0 | 50.8 | 19.9 | 10.8 | 8.1 | 7.6 | 7.5 | 7.4 |
| Myalgia | 47.8 | 9.0 | 47.9 | 19.2 | 9.7 | 6.6 | 5.3 | 4.6 | 4.4 |
| Fever | 34.7 | 4.8 | 37.0 | 8.3 | 2.8 | 1.8 | 1.4 | 1.2 | 1.2 |
| Chills | 34.2 | 5.5 | 35.7 | 6.7 | 2.3 | 1.4 | 1.2 | 1.0 | 1.0 |
| Joint pain | 26.1 | 3.5 | 25.3 | 8.9 | 4.5 | 3.3 | 2.8 | 2.6 | 2.4 |
| Nausea | 18.7 | 3.8 | 15.7 | 5.4 | 3.5 | 2.6 | 2.1 | 1.9 | 1.7 |
| Diarrhea | 9.4 | 0.9 | 4.3 | 3.4 | 2.7 | 2.1 | 1.7 | 1.5 | 1.5 |
| Swelling | 9.3 | 1.8 | 4.6 | 4.6 | 4.4 | 3.9 | 2.9 | 2.1 | 1.5 |
| Abdominal pain | 7.4 | 0.9 | 5.0 | 2.2 | 1.6 | 1.3 | 1.2 | 1.1 | 1.1 |
| Redness | 7.4 | 1.2 | 2.5 | 4.0 | 4.1 | 3.4 | 2.4 | 1.6 | 1.0 |
| Itching | 7.1 | 1.2 | 1.8 | 2.6 | 3.2 | 3.0 | 2.5 | 1.8 | 1.4 |
| Vomiting | 2.1 | 0.2 | 1.6 | 0.4 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 |
| Rash | 1.9 | 0.2 | 0.5 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 |
| Any injection sitereaction§ | 60.7 | 33.1 | 50.3 | 41.8 | 33.1 | 24.1 | 15.9 | 9.7 | 6.6 |
| Any systemicreaction¶ | 76.4 | 29.8 | 74.8 | 44.1 | 28.9 | 22.3 | 19.7 | 18.2 | 17.3 |
| Any healthimpact** | 33.9 | 4.8 | 33.2 | 9.7 | 5.1 | 3.8 | 3.3 | 3.1 | 3.1 |
| Unable to perform normal dailyactivities | 28.3 | 3.8 | 27.7 | 7.4 | 4.0 | 3.0 | 2.6 | 2.5 | 2.5 |
| Unable to work | 17.0 | 1.8 | 16.3 | 4.5 | 2.0 | 1.3 | 1.0 | 1.0 | 0.9 |
| Needed medical care | 1.4 | 0.1 | 0.4 | 0.2 | 0.3 | 0.3 | 0.3 | 0.4 | 0.4 |
| Telehealth | 0.53 | 0.02 | 0.16 | 0.09 | 0.11 | 0.12 | 0.11 | 0.12 | 0.12 |
| Clinic | 0.40 | 0.03 | 0.05 | 0.05 | 0.07 | 0.10 | 0.11 | 0.12 | 0.12 |
| Emergency visit | 0.31 | 0.04 | 0.08 | 0.05 | 0.06 | 0.06 | 0.07 | 0.07 | 0.06 |
| Hospitalization | 0.04 | 0.00 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 |
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* Proportion of enrollees who reported a reaction or health impact at leastonce during postvaccination days 0–7.
† Enrollees were able to respond on multiple days.
§ Injection site pain, swelling, redness, or itching.
¶ Fatigue, headache, myalgia, fever, chills, nausea,diarrhea, abdominal pain, vomiting, or rash at injection site.
** A health impact was defined as being unable to perform normal dailyactivities, being unable to work, or receiving medical care.
Discussion
A review of postauthorization safety data after administration of 7.98 million dosesof Janssen COVID-19 vaccine during March–April 2021 found that the mostcommonly reported reactions were similar to those observed in the preauthorizationtrials (2). Among processedVAERS reports, 97% were classified as nonserious events. However, reports included17 events consistent with TTS, a newly defined condition, including three reports ofnon-CVST thrombotic events with thrombocytopenia among women aged <60 yearsduring the pause in Janssen vaccine use. Among 88 deaths reported after vaccination,three occurred in patients with CVST (8); after preliminary reviews, no other deathsappear to have an association with vaccination.
Two other COVID-19 vaccines, both using an mRNA platform, were authorized for use asa 2-dose series before the Janssen vaccine received authorization. The Janssenadenoviral vector vaccine only requires a single dose for substantial protectionfrom COVID-19 and can be stored at refrigerator temperatures (2). Because of these advantages, some healthjurisdictions and providers have used the Janssen COVID-19 vaccine among persons forwhom ensuring a second dose might be difficult or in settings such as collegecampuses or drive-through vaccination sites where simple storage requirements areimportant.¶¶¶ In an update of recommendations foruse of the Janssen COVID-19 vaccine, ACIP considered the balance between thesebenefits and a rare but serious safety concern, the risk for thrombosis in largearteries or veins (10). OnApril 23, 2021, after a review of the benefits and risks, ACIP reaffirmed itsinterim recommendation for use of the Janssen COVID-19 vaccine in all persons aged≥18 years under the FDA’s EUA (10). The EUA now includes a warning for rareclotting events with low platelets, primarily occurring among women aged18–49 years.
The findings in this report are subject to at least three limitations. First, VAERSdata are based on a well-established but passive surveillance system (9). Reporting differences arelikely, in part because of the EUA requirement that health care providers report allpotentially life-threatening events after receipt of the Janssen COVID-19 vaccine.Second, a comprehensive medical review of reported serious adverse events aftervaccination, particularly deaths, depends on the availability of medical records,death certificates, and autopsy reports. For many of the serious adverse eventsreported after vaccination to date, these reviews are in progress. Finally, althoughv-safe is an important new component of the U.S. COVID-19 vaccine safety monitoringsystem, participation is contingent on promotion by vaccine administrators and anopt-in enrollment system that uses text messages. Therefore, v-safe data might notbe generalizable to the entire population of persons who have received the JanssenCOVID-19 vaccine.
The safety profile thus far of the Janssen COVID-19 vaccine is similar to thatobserved in clinical trials. A rare but serious adverse event occurring primarily inwomen, blood clots in large vessels accompanied by a low platelet count, was rapidlydetected by the U.S. vaccine safety monitoring system. Monitoring for common andrare adverse events after receipt of all COVID-19 vaccines, including the JanssenCOVID-19 vaccine, is continuing. Safety data will be evaluated by ACIP as needed toguide benefit-risk assessments of COVID-19 vaccines in use under EUAs.
Summary.
What is already known about this topic?
An Emergency Use Authorization of the Janssen COVID-19 vaccine was grantedFebruary 27, 2021. Use was paused during April 12–23, 2021, afterdetection of six cases of cerebral venous sinus thrombosis (CVST).
What is added by this report?
By April 21, nearly 8 million doses of the Janssen COVID-19 vaccine had beenadministered. Review of safety monitoring data found that 97% of reportedreactions after vaccine receipt were nonserious, consistent withpreauthorization clinical trials data. Seventeen thrombotic events withthrombocytopenia have been reported, including three non-CVST events.
What are the implications for public health practice?
Ongoing monitoring for rare and common adverse events after vaccination isimportant for evaluating the balance between risks and benefits for eachauthorized COVID-19 vaccine, including the Janssen COVID-19 vaccine.
Acknowledgment
Rita F. Helfand, CDC.
All authors have completed and submitted the International Committee ofMedical Journal Editors form for disclosure of potential conflicts ofinterest. No potential conflicts of interest were disclosed.
Footnotes
*
The Janssen COVID-19 vaccine contains double-stranded DNA encoding a variant ofthe SARS-CoV-2 spike glycoprotein inserted into a replication-incompetent humanadenovirus type 26 virus.
†
VAERS reports are classified as serious if any of the following are reported:death, life-threatening illness, hospitalization or prolongation ofhospitalization, permanent disability, congenital anomaly, or birth defect.
§
Brighton Collaboration’s draft interim case finding definition for TTS:any patient presenting with acute venous or arterial thrombosis and new onsetthrombocytopenia, with no known exposure to heparin or any other underlyingcondition or explanation for the condition. https://brightoncollaboration.us/wp-content/uploads/2021/04/TTS-Case-Finding-and-Definition-Process.v1.0-1-1.pdf
¶
A health impact was defined as being unable to perform normal daily activities,being unable to work, or receiving medical care.
††
Each VAERS report might be assigned more than one MedDRA preferred term. A MedDRAcoded event does not indicate a medically confirmed diagnosis. https://www.meddra.org/how-to-use/basics/hierarchy
¶¶
CDC has encouraged jurisdictions receiving COVID-19 vaccines to offer v-safepromotional materials, supplied by CDC, at all vaccination sites. V-safeenrollees receive daily health check-ins via text messages that link toweb-based surveys on days 0–7 after vaccination; then weekly through 6weeks after vaccination; and then 3, 6, and 12 months after vaccination.
***
45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. Sect. 241(d); 5 U.S.C. Sect.552a; 44 U.S.C. Sect. 3501 et seq.
†††
Processed VAERS reports are reports that have been coded using MedDRA, have beendeduplicated, and have undergone standard quality assurance and quality controlreview.
§§§
Medical reviews were conducted by CDC and FDA staff physicians, who reviewed allavailable data, including medical records, death certificates, and autopsyreports, to form preliminary impressions about the cause of death for eachdecedent. These reviews might be ongoing for some decedents.
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