In part three of the new immunization series, Stanley E. Grogg, DO, FACOP, FAAP, interprets footnotes and addresses questions regarding pediatric and adolescent vaccines, including COVID-19, hepatitis B, rotavirus, diphtheria, tetanus, pertussis, Haemophilus type B, pneumococcal, inactivated poliovirus and combination vaccines.
By Stanley E. Grogg, DO, FACOP, FAAP; AOA Liaison Member to the CDC’s Advisory Committee on Immunization Practices (ACIP)
Each year, toward the end of February, the pediatric immunization schedules are published by the U.S. Centers for Disease Control and Prevention (CDC). The schedules are first reviewed and approved by the American Academy of Pediatrics (AAP), the American Academy of Family Physicians (AAFP), the American College of Obstetricians and Gynecologists, and the Advisory Committee on Immunization Practices (ACIP).1 Many times, a healthcare provider (HCP) needs more information than what is found in the immunization schedule table. Most of the specific answers are found in the footnotes of the pediatric immunization schedules. Parts one and two for adult vaccine questions have been published in recent ACOFP blogs.
This blog discusses many of the questions HCPs ask about pediatric immunizations. Part one will include an update of the COVID-19 vaccines for adolescents—including a discussion on myocarditis, which is associated with mRNA vaccines. In addition, hepatitis B, combination vaccines, rotavirus, diphtheria, tetanus, pertussis, Haemophilus type B, pneumococcal, and the inactivated poliovirus vaccines will be reviewed in this blog. In the pediatric part two blog, the influenza, measles, mumps, rubella, varicella, hepatitis A, human papillomavirus and meningococcal vaccines will be discussed. Vaccine schedules and footnotes are included for references. The use of trade names is for identification purposes only and does not imply endorsements by the ACIP or CDC. To stay up to date on immunizations, the CDC Vaccine Schedule app can be downloaded at no cost.
Q: A five-year-old child is brought to the office by her grandmother, who has a note giving permission to care for the child. Her grandmother also has the child’s immunization record, which indicates the child has had two doses of the recommended three doses of Hepatitis B vaccine, one at birth and one at 2 months of age. Should you restart the Hepatitis B series?
A: No. One should not restart or add doses to a child’s vaccine series if there are extended intervals between doses. When a vaccine is not administered at the recommended age, continue on the series as recommended in the catch-up schedule. (Table 2, Footnote 3)
Q: What COVID-19 vaccines are recommended for pediatric patients?
A: The ACIP recommends use of COVID-19 vaccines for everyone ages 12 and older within the scope of the Emergency Use Authorization (EUA) for the particular vaccine. As of July 2, the CDC Interim Clinical Statement states, “Children outside these authorized age groups should not receive COVID-19 vaccination at this time.6 Presently, the Pfizer-BioNTech COVID-19 vaccine is approved for 12 years of age and older.4 Moderna, currently recommended for 18 years of age and older, has applied to the U.S. Food and Drug Administration (FDA) for EUA use at 12 years of age and older and may have been approved as of this publication.5 Presently, Pfizer is conducting studies for ages 5–12 years with a reduced dose of vaccine.6
Q: Other than the common local injection type of tenderness, swelling, redness and tiredness with or without fever for a few days, are there any other particular side effects or warnings which have been reported from the Pfizer vaccine for 12 years or other mRNA vaccines (Moderna)?
A: Yes, the CDC is monitoring reports of myocarditis and pericarditis in the mRNA vaccines. Since April 2021, there have been more than a thousand reports to the Vaccine Adverse Event Reporting System (VAERS) of cases of inflammation of the heart—called myocarditis and pericarditis—happening after mRNA COVID-19 vaccination (i.e., Pfizer-BioNTech, Moderna) in the United States. These reports are rare, given the hundreds of millions of vaccine doses administered, and have been reported after mRNA COVID-19 vaccinations, particularly in adolescents and young adults. The CDC and its partners are actively monitoring these reports, by reviewing data and medical records, to learn more about what happened and to understand any relationship to COVID-19 vaccination. Most patients who received care responded well to treatment and rest and quickly felt better. Confirmed cases have occurred:
- Mostly in male adolescents and young adults aged 16 years or older
- More often after getting the second dose of a mRNA COVID-19 vaccine
- Typically within several days after COVID-19 vaccination
Patients can usually return to their normal daily activities after their symptoms improve. They should speak with their doctor about returning to exercise or sports.
The CDC continues to recommend COVID-19 vaccination for everyone 12 years of age and older, given the risk of COVID-19 illness and related—possibly severe—complications. Being vaccinated is the best way to help protect yourself and your family from COVID-19.7 As of April 23, 2021, the FDA added the following warning to the provider fact sheet of the Moderna vaccine: “Thrombosis with Thrombocytopenia Reports of adverse events following use of the Janssen COVID-19 vaccine under emergency use authorization suggest an increased risk of thrombosis involving the cerebral venous sinuses and other sites (including but not limited to the large blood vessels of the abdomen and the veins of the lower extremities) combined with thrombocytopenia and with onset of symptoms approximately one to two weeks after vaccination. Most cases of thrombosis with thrombocytopenia reported following the Janssen COVID-19 vaccine have occurred in females ages 18 through 49 years; some have been fatal. The clinical course of these events shares features with autoimmune heparin-induced thrombocytopenia. In individuals with suspected thrombosis with thrombocytopenia following the Janssen COVID-19 vaccine, the use of heparin may be harmful and alternative treatments may be needed. Consultation with hematology specialists is strongly recommended. The American Society of Hematology has published considerations relevant to the diagnosis and treatment of thrombosis with thrombocytopenia following the Janssen COVID-19 vaccine.”19
Q: Can the COVID-19 vaccines be administered with other vaccines on the same day?
A: Yes, COVID-19 vaccines and other vaccines may be administered on the same day without regard to timing. The CDC also states that It is unknown whether reactogenicity of COVID-19 vaccine is increased with co-administration, including with other vaccines known to be more reactogenic, such as adjuvanted vaccines or live vaccines. When deciding whether to co-administer another vaccine(s) with COVID-19 vaccine, vaccination providers should consider whether the patient is behind or at risk of becoming behind on recommended vaccines, their risk of vaccine-preventable disease (e.g., during an outbreak or occupational exposures) and the reactogenicity profile of the vaccines.” So if a child is totally up to date on their immunizations, it may be prudent to separate COVID-19 vaccine from non-emergent vaccines in case there is a reaction to the COVID-19 vaccine. However, if you have a pediatric patient that is not good at getting vaccines, it would be okay to give them at the same time now. If multiple vaccines are administered at a single visit, administer each injection in a different injection site. For adolescents and adults, the deltoid muscle can be used for more than one intramuscular injection.9
Q: Can COVID-19 vaccine providers charge for administration of the COVID-19 vaccination?
A: Yes. COVID-19 vaccination providers can seek appropriate reimbursement from the recipient’s plan or program for a vaccine administration fee but cannot charge for the vaccine.10
Q: Should COVID-19 vaccine be given to a pediatric patient after COVID-19 infection?
A: YES. Although the CDC does not have a specific recommendation presently for pediatric patients, people with prior or current SARS-CoV-2 infection. People should be offered vaccination regardless of their history of symptomatic or asymptomatic SARS-CoV-2 infection. Data from clinical trials indicate that the currently authorized COVID-19 vaccines can be given safely to people with evidence of a prior SARS-CoV-2 infection. Viral testing to assess for acute SARS-CoV-2 infection or serologic testing to assess for prior infection is not recommended for the purposes of vaccine decision-making.20
Hepatitis B (HepB) Vaccine (Table 1, Footnote 3)
Q: Why does a newborn need a HepB Vaccine?
A: Hepatitis B is a serious disease caused by the hepatitis B virus. The virus can enter the bloodstream, attack the liver and cause serious damage. When babies become infected, the virus usually remains in the body for a lifetime; this is called chronic hepatitis B. About one out of four infected babies will die of liver failure or liver cancer as adults. Hepatitis B is a deadly disease—but it’s preventable with vaccination.11
Q: Since HepB is a single component vaccine for the newborn, can the child receive four HepB rather than three vaccinations if given as a combination vaccination?
A: Yes. The routine HepB series is recommended as three doses at 0, 1–2 and 6–12 months. Administration of four doses is permitted when a combination vaccine containing HepB is used after the birth dose. (Footnote 3)
Q: What is the recommendation for HepB if the mother is hepatitis B surface antigen (HBsAg)-positive or if the mother’s HBsAg status is unknown?
A: If the mother is HBsAg-positive, administer HepB vaccine and hepatitis B immune globulin (HBIG) in separate limbs within 12 hours of birth, regardless of the birth weight. For infants under 2000 grams, administer three additional doses of vaccine (total of four doses) beginning at one month.
Test for HBsAg and anti-HBs when the infant is 9–12 months old. If the HepB series is delayed, test 1–2 months after the final dose.
For mothers whose HBsAg status is unknown, administer the HepB vaccine within 12 hours of birth, regardless of birth weight. For infants under 2000 grams, administer HBIG, in addition to the HepB vaccine, in separate limbs within 12 hours of birth. Administer three additional doses of vaccine (total of four doses) beginning at one month. Determine the mother’s HBsAg status as soon as possible. If the mother is HBSAg-positive, administer HBIG to infants more than 2000 grams as soon as possible, but no later than seven days of age. (Footnote 3).
Q: If a 15-year-old adolescent has not received any HepB vaccinations, what does the ACIP recommend?
A: There are two options for a 15-year-old for HepB vaccinations:
- Complete a three-dose series at zero, 1–2 and six months.
- Give two doses of Adult Recombivax HEB at least four months between doses which is approved for 11–15 years of age. (Footnote 3)
For adolescents 18 years and older, a HCP may give a two-dose series of HepB (Heplisav-B by Dynavax) at least four weeks apart or the combined HepA and HepB vaccine (Twinrix, by GSK) as a three-dose series—at zero, one and six months—or 4-dose series—three doses at zero, seven and 21–30 days, followed by a booster dose at 12 months. (Footnote 3)
Rotavirus (Table 1, Footnote 4)
Q: What are the recommendations for the rotavirus vaccinations, routine and catch-up?
A: The minimum age for administration of the rotavirus vaccine is six weeks. For catch-up, the series should not be started on or after the age of 15 weeks, 0 days. The maximum age for the final dose is eight months, 0 days. Rotarix by GSK is a two-dose series recommended at two and four months, and RotaTeq by Merck is a three-dose series at two, four and six months.
Q: A four-month-old comes to the office without an immunization card and is from out of state. The mother states that her child received her two-month immunizations. Which rotavirus vaccine should be given?
A: If any dose in the series of rotavirus vaccine is either RotaTeq or unknown, assume the initial dose was RotaTeq and default to a three-dose series. (Footnote 4)
Diphtheria, Tetanus and Pertussis (DTaP) Vaccinations: Part 1 (Table 1, Footnote 1)
Q: What are the indications of DTaP? (Footnote 1)
A: DTaP can be used at the minimum age of six weeks old, with a maximum age of six years old. For Kinrix by GSK and Quadracel by Sanofi, the minimum age is four years old, with a maximum age of six years old. For routine vaccinations, DTaP is a five-dose series at two, four, six and 15–18 months, and 4–6 years of age. (Footnote 1)
Q: A 12-month-old child is brought to your office. The mother would like for her child to receive her booster pertussis vaccination. What would the ACIP recommend?
A: The child may receive a DTaP, if at least six months have elapsed since dose three. For instance, if dose one was at six weeks old, dose two at three months old (more than six weeks) and dose three at five months old, then dose four could be given at 12 months of age. (Footnote 1)
Q: A child had only received three doses of DTaP before age four. Will they need one or two more doses to complete the series?
A: Only four doses of DTaP are required if dose four was administered at or after age four, at least six months after the third dose of DTaP. (Footnote 1)
Q: At what age can Tdap be used?
A: Tdap for routine vaccination is recommended at age 11–12 years old with one dose. Tdap can be used as early as age seven for catch-up doses. Afterward, Td or Tdap can be used every 10 years. (Footnote 4)
Q: How should a dirty wound in an eight-year-old who only received his initial three DTaP vaccinations at two, four and six months be handled?
A: Persons who have completed a three-dose primary tetanus vaccination series, as this child, should receive a dose of Tdap since the last dose of tetanus-toxoid-containing vaccine was received more than five years earlier. This will also give this child protection from pertussis. (Footnote 1)
Q: What is the ACIP recommendation if an eight-year-old is inadvertently administered a DTaP instead of a Tdap?
A: Children aged 7–9 years old who were inadvertently administered a DTaP instead of a Tdap may count the DTaP as part of a catch-up series. They should be given a Tdap dose at age 11–12 years. Children aged 10–18 years old who were inadvertently administered a DTaP can count the dose as the adolescent Tdap booster. (Footnote 4)
Q: An eight-year-old patient has a dirty laceration of the arm. After thoroughly cleaning the area with soap and water, what is the recommended protocol for a tetanus vaccination?
A: An eight-year-old with a “dirty” wound should follow the following recommendations under number 2 below. Patients seven years of age and older with a history of three or more doses of tetanus-toxoid-containing vaccine should be:
- Administered Tdap or Td if more than 10 years since the last dose of tetanus-toxoid-containing vaccine—for clean and minor wounds.
- Administered Tdap or Td if more than 5 years since the last dose of tetanus-toxoid-containing vaccine—for all other wounds. Tdap is preferred for a person aged 11 or older and who did not previously receive a Tdap or whose Tdap history is unknown. If a tetanus-toxoid-containing vaccine is indicated for a pregnant adolescent, use Tdap. (Footnote 4)
Haemophilus Type B (HiB) Vaccine (Tables 1, 2 and 3, Footnote 1)
Q: Several formulations of HiB vaccines are available. What are the recommendations for the various brands of HiB?
A: ActHIB (by Sanofi Pasteur), Hiberix (by GSK) and Pentacel (by Sanofi), are all four-dose series that are recommended at two, four, six and 12–15 months of age. PedvaxHIB (by Merck) is recommended as a three-dose series, recommended at two, four and 12–15 months. (Footnote 1)
Q: A 15-month-old, low-risk child is scheduled for a routine check-up. On reviewing the child’s immunization record, it is noted that only one HiB vaccine has been given—a PedvaxHIB at two months of age. Otherwise, the child is up-to-date on immunizations. What is recommended for this child’s catch-up for the HiB vaccine?
A: The HiB catch-up schedule is somewhat complicated as follows:
- If dose one was given at 7–11 months old, administer dose two at least four weeks later and dose three (the final dose) at 12–15 months of age or eight weeks after dose two—whichever is later.
- If dose one was given at 12–14 months old, administer dose two (the final dose) at least eight weeks after dose one.
- If dose one was given before 12 months of age and dose two before 15 months of age, administer dose three (the final dose) eight weeks after dose two.
- If two doses of PedvaxHIB were given before 12 months of age, administer dose three (the final dose) at 12–59 months old and at least eight weeks after dose two.
- If one dose was administered at age 15 months or older, no further doses are needed.
- If a child is unvaccinated at 15–59 months old, administer one dose.
- If a child is unvaccinated at 60 months or older and not considered high-risk, the child does not require catch-up vaccination.
Thus, the low-risk, 15-month-old child coming to the office with only one HiB vaccine at two months old only needs one HiB vaccine for catch-up. If the child was 60 months or older, no HiB would be recommended.
Q: If a two-year-old patient has a successful hematopoietic stem cell transplant (HSCT), are any HiB vaccinations recommended?
A: Yes, a three-dose series four weeks apart, starting 6–12 months after a successful transplant, is recommended regardless of HiB vaccination history.
Q: Should an infant with sickle cell disease receive any HiB vaccinations?
A: Yes, all children with anatomic or functional asplenia, such as sickle disease, should receive the HiB vaccination series. If an anatomic or functional asplenia patient 12–59 months of age presents to the office with a history of no HiB vaccines or only one HiB vaccine before the age of 12 months, two doses of HiB at eight weeks apart should be given. If two or more doses of HiB vaccine before age 12 months have been given, only one dose of HiB at least eight weeks after the previous dose is needed. If a patient is having an elective splenectomy and is age 15 months or older without a history of a HiB vaccination, they should receive one dose of HiB at least 14 days before the procedure. (Footnote 1)
Q: Are there any special recommendations for HiB vaccination for Native American infants?
A: Yes, because of the risk of invasive HiB disease at younger ages in Native Americans, the Indian Health Service (IHS) has recommended a preference for the PRP-OMP (PEDVAXHIB by Merck) HiB conjugate vaccine based on seroconversion rates of 60% after the first dose of PRP-OMP, compared with rates of only 20% for other HiB conjugate vaccines.14
Q: A 10-year-old child has been diagnosed with HIV; should this child receive a HiB vaccination?
A: Yes, unvaccinated children, 5–18 years old with the diagnosis of HIV should receive one dose of HiB. (Tables 1, 2 and 3, Footnote 1)
Pneumococcal Vaccinations (Tables 1, 2, and 3, Footnote 2)
Q: What is the difference between PPSV23 (Pneumovax 23 by Merck) and PCV13 (Prevnar13 by Pfizer)
A: The two vaccines used in the United States are PPSV23 (polysaccharide) and PCV13 (conjugated) to help protect against pneumococcal disease. These vaccines are effective at preventing severe pneumococcal disease, which often requires treatment in the hospital and can be deadly. However, these vaccines will not prevent all infections. The PCV13 is a conjugate vaccine and can be used in infants six weeks of age or older. The PPSV23 is a polysaccharide vaccine and does not stimulate an immune response under two years old.14
Q: What are the routine indications for PCV13 and for catch-up vaccination?
A: For routine vaccination, PCV13 should be given as four doses at two, four, six and 12–15 months old. For catch-up immunization, one dose for healthy children aged 24–59 months with any incomplete PCV13 series is indicated. (Table 2, Footnote 2)
Q: A two-year-old child has severe asthma and is being treated with high-dose of oral steroids. The patient has received PCV13 at two, four, six and 12 months of age. Are any other pneumococcal vaccines recommended?
A: Yes, children with certain underlying medical conditions—including chronic heart disease, chronic lung disease, such as severe asthma, and diabetes mellitus—at two years old should receive an additional PPSV23 immunization. When both a PCV13 and PPSV23 are indicated, the PCV13 should be given first and PPSV23 two months later. Do not give the PCV13 and PPSV23 at the same visit.
Q: Should PPSV23 be given at two years of age for patients with asplenia or functional asplenia, such as sickle cell disease?
A: Yes, they should be up-to-date with PCV13 and given PPSV23. This includes patients with several disorders, including sickle cell disease and other hemoglobinopathies, congenital or acquired immunodeficiency, HIV infection, chronic renal failure, nephrotic syndrome, malignant neoplasms, leukemias, lymphomas, Hodgkin disease and other diseases associated with treatment with immunosuppressive drugs or radiation therapy, solid organ transplantations and multiple myeloma. For all indications of pediatric special circumstances for pneumococcal disease, see Table 3 and footnote 2.
Q: Are additional pneumococcal vaccines anticipated in the future?
A: Yes. At the ACIP October 2020 and June 2021 meetings, two new pneumococcal products were reviewed. One is produced by Merck (PCV15) and one by Pfizer (PCV20). Pneumococcal serotypes will be covered as follows:15,16
PCV20 by Pfizer was approved by the FDA on June 9, 2021, and PCV15 by Merck is expected approval in July 2021. Licensure for children is anticipated in February 2022.17
Inactivated Poliovirus (IPV) Vaccine (Table 1, Footnote 4)
Q: Since polio is almost eliminated in the world and no recent cases have occurred in the United States, is the IPV vaccine still recommended?
A: Yes. Polio has not been totally eradicated in the world. The IPV is recommended routinely as four doses at two, four, six and 18 months and 4–6 years of age. The IPV can be given as young as six weeks old. The oral polio vaccination (OPV) is no longer available in the United States because OPV is a live virus and rare cases of polio have occurred from the vaccine. IPV is not routinely recommended after 18 years of age. Guidance for travel and use of IPV can be found in footnote four.
Q: What is the recommendation of the ACIP for combination vaccinations?
A: The use of licensed combination vaccines are preferred over separate injections if equivalent component vaccines with the exception the MMRV at 12 months of age described under varicella vaccination section. Only combinations approved by the FDA should be used.12
Q: What are the combination vaccines which are recommended for pediatric patients?
A: Pediatric combination vaccines include the following:
- DTaP, HepB and inactivated poliovirus vaccine DTaP-HepB-IPV Pediarix® by GSK
- DTaP, IPV, and HiB vaccine DTaP-IPV/Hib Pentacel® by Sanofi Pasteur
- DTaP and IPV DTaP-IPV Kinrix® by GSK and Quadracel® by Sanofi Pasteur
- MMR and VAR vaccine MMRV ProQuad® by Merck
- DTaP, IPV, HiB and HepB12 vaccine Vaxelis® by Merck/Sanofi Pasteur (newest)13
- Who Sets the Immunization Schedule? https://www.cdc.gov/vaccines/parents/schedules/sets-schedule.html. (Accessed 6/13/2021)
- 2021 CDC Pediatric Vaccine Schedules: https://www.cdc.gov/vaccines/schedules/downloads/child/0-18yrs-child-combined-schedule.pdf (Accessed 6/13/2021)
- Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Authorized in the United States: https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fvaccines%2Fcovid-19%2Finfo-by-product%2Fclinical-considerations.html (Accessed 6/13/2021).
- Approved Adolescent/Teens COVID-19 Vaccines: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/Pfizer-BioNTech.html (Accessed 6/13/2021)
- Moderna Applies for EUA for Teens: https://investors.modernatx.com/news-releases/news-release-details/moderna-files-emergency-use-authorization-its-covid-19-vaccine. (Accessed 6/13/2021)
- Pfizer Announces COVID-19 Clinical Trials for 5–11 Years of Age. https://abcnews.go.com/Health/pfizer-advances-clinical-trials-11-year-olds-lower/story?id=78148963 (Accessed 6/13/2021)
- Investigation of mRNA and Myocarditis/Pericarditis: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/myocarditis.html. (Accessed 6/25/2021)
- The FDA Is Adding a Warning to the mRNA Fact Sheets: https://www.healio.com/news/cardiology/20210623/cdc-benefits-of-covid19-messenger-rna-vaccines-outweigh-myocarditis-risks.
- COVID-19 Vaccine Co-administered With Other Vaccines: https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fvaccines%2Fcovid-19%2Finfo-by-product%2Fclinical-considerations.html#Coadministration (Accessed 6/13/2021)
- COVID-19 Claims Reimbursement to Health Care Providers and Facilities for Testing, Treatment, and Vaccine Administration for the Uninsured https://www.hrsa.gov/coviduninsuredclaim (Accessed 6/13/2021)
- Why Newborns Need a HepB Vaccine: https://www.immunize.org/catg.d/p4110.pdf. (Accessed 7/2/2021)
- ACIP Recommendation for Combination Vaccines: https://www.cdc.gov/mmwr/preview/mmwrhtml/rr4805a1.htm. (Accessed 6/13/2021)
- New Hexavalent Pediatric Vaccine, Known as Vaxelis: https://www.contagionlive.com/view/cdc-issues-guidance-for-hexavalent-vaccine-in-children (Accessed 6/13/2021)
- Special HiB Recommendations for American Indian Children: https://pediatrics.aappublications.org/content/104/3/564.short. (Accessed 6/15/2021)
- Pneumococcal Vaccines: https://www.cdc.gov/pneumococcal/vaccination.html. (Accessed 6/16/2021)
- Pneumococcal Slide Presentation at the ACIP October 2020 Meeting Concerning PCV20 and PCV15: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2020-10/pneumo-01-Poehling-Kobayashi-508.pdf (Accessed 6/16/2021)
- Anticipated Timeline for Approval of PCV20 and PCV15 by the FDA and ACIP: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-02/24-25/01-Pneumococcal-Poehling.pdf. (Accessed 6/26/2021)
- FDA Approval of Pfizer’s PCV20 vaccine on June 9, 2021: https://www.pharmacypracticenews.com/FDA-Approvals/Article/06-21/FDA-Approves-Prevnar-20-Pneumonia-Vaccine-for-Adults-/63781. (Accessed 6/26/2021)
- FDA Added Warning for Providers for Use of Johnson & Johnson Vaccine for Possible Thrombosis: https://www.hematology.org/covid-19/vaccine-induced-immunethrombotic-thrombocytopenia. (Accessed 7/7/2021)
- COVID-19 Vaccine After COVID-19 Infection: https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html#CoV-19-vaccination (Accessed 7/7/2021)
Note: The CDC website is a public domain website, is not subject to copyright and may be freely used or reproduced without obtaining copyright permission. https://www.cdc.gov/other/agencymaterials.html. (Accessed 05/22/2021)