Moreover, SMFM states that for breastfeeding mothers, the biological plausibility of harm to the child is essentially nil.11 Even if the mRNA or lipid packaging of the vaccine made its way into breastmilk (unlikely), the child’s own digestive tract would metabolize it such that even if such substances were somehow dangerous (though they are not believed to be), the exposure risk actually approaches zero. Currently, only smallpox and yellow fever vaccines are contraindicated for breastfeeding mothers, as they are based on live-attenuated viruses.
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ACEP Now: Vol 40 – No 01 – January 2021For more information regarding COVID-19 vaccines, follow the CDC and Infectious Diseases Society of America.
| Pfizer-BioNTech | Moderna | |
|---|---|---|
| Age indications | ≥16 years old | ≥18 years old |
| Contraindications | History of severe allergic reaction to any component of the vaccine | |
| Storage temperature | –80°C and –60°C | –25°C and –15°C |
| Number of doses | 2 | 2 |
| Scheduled dosing | 21 days apart | 28 days apart |
| Dosing caveats | Must be within ≤4 days, though there is no maximum interval between doses | |
| Route of administration | Intramuscular in the deltoid muscle | |
| Emergency use authorization | Dec. 11, 2020 | Dec. 18, 2020 |
| Overall efficacy at preventing symptomatic COVID-19 (positive RT-PCR plus symptoms) 7 or 14 days after receiving dose 1 and 2 (95% CI) | Reported as after 7 days: No prior infection: 95% (90.3%, 97.6%); With or without prior infection: 94.6% (89.9%, 97.3%) | Reported as after 14 days: ~94% (86.5%, 97.8%) |
| Efficacy between dose 1 and 2 | 52.4% (29.5%, 68.4%) | Reported as only receiving dose 1: First 14 days: 50.8% (–53.6%, 86.6%); >14 days: 92.1% (68.8%, 99.1%) |
| Overall efficacy within 7 days or 14 days after receiving dose 1/2 | Reported as within 7 days: 90.5% (61%, 98.9%); Reported as within 14 days: not yet reported | Not reported |
| Subgroup efficacy after dose 2 | 16–64 years: 95.1% (89.6, 98.1); ≥65 years old: 94.7% (66.7, 99.9) | 18–64 years: 95.6% (90.6, 97.9); ≥65 years old: 86.4% (61.4, 95.2) |
| Efficacy at preventing severe COVID-19 | Overall: 88.9% (20.1, 99.7) (Only 1 case in the vaccine group, which occurred at ≥7 days after dose 2; no cases occurred before dose 2) | Dose 1: 42.6% (–300.8%, 94.8%); Dose 1+2: 100% (no 95% CI given) |
| Common side effects | Injection site pain, tiredness, headache, muscle pain, chills, joint pain, fever | Injection site pain, tiredness, headache, muscle pain, chills, joint pain, swollen lymph nodes in the same arm as the injection, nausea and vomiting, fever |
| Rare side effects | Severe allergic reaction (reported outside of clinical trial data) | Bell’s palsy, intractable nausea and vomiting (no causal link identified) |
| Notable side effects for dose 2 compared to dose 1 | Fever, fatigue, headache, chills, myalgias, arthralgias | Fever, fatigue, headache, chills, myalgias, arthralgias, nausea and vomiting, axillary swelling/tenderness, injection site erythema |
| Concomitant vaccination | Minimum interval of 14 days before or after administration with any other vaccines | |
| Booster doses | No data beyond two doses | |
| Previous SARS-CoV-2 infection | It is recommended that people with previous infection with SARS-CoV-2 get the vaccine, and it appears safe in clinical trials subgroup analyses. Asymptomatic testing prior to vaccination is not recommended. Individuals who are symptomatic should wait until they are asymptomatic. | |
| Previous treatment with monoclonal antibodies or convalescent plasma | CDC recommends waiting 90 days after treatment with either monoclonal antibodies or convalescent plasma before vaccination. | |
References
- Voysey M, Clemens SAC, Madhi SA, et al. 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 [published online ahead of print Dec. 8, 2020]. Lancet. doi: 10.1016/S0140-6736(20)32661-1.
- AFP. AstraZeneca: ‘Winning’ vaccine formula is 100% effective against severe COVID-19. The Times of Israel website. Available at: https://www.timesofisrael.com/astrazeneca-winning-vaccine-formula-is-100-effective-against-severe-covid-19. Accessed Dec. 28, 2020.
- Moderna COVID-19 vaccine. CDC website. Available at: https://www.cdc.gov/vaccines/covid-19/info-by-product/moderna/index.html. Accessed Dec. 28, 2020.
- FDA briefing document: Moderna COVID-19 vaccine. FDA website. Available at: https://www.fda.gov/media/144434/download. Accessed Dec. 28, 2020.
- Pfizer-BioNTech COVID-19 vaccine. CDC website. Available at: https://www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/index.html. Accessed Dec. 28, 2020.
- Review of efficacy and safety of Pfizer-BioNTech COVID-19 vaccine emergency use authorization request. FDA website. Available at: https://www.fda.gov/media/144337/download. Accessed Dec. 28, 2020.
- Interim clinical considerations for use of mRNA COVID-19 vaccines currently authorized in the United States. CDC website. Available at: https://www.cdc.gov/vaccines/covid-19/info-by-product/clinical-considerations.html. Accessed Dec. 28, 2020.
- COVID-19 ACIP vaccine recommendations. CDC website. Available at: https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/covid-19.html. Accessed Dec. 28, 2020.
- Vaccinating pregnant and lactating patients against COVID-19. American College of Obstetricians and Gynecologists website. Available at: https://www.acog.org/Clinical/Clinical%20Guidance/Practice%20Advisory/Articles/2020/12/Vaccinating%20Pregnant%20and%20Lactating%20Patients%20Against%20COVID%2019. Accessed Dec. 28, 2020.
- Coronavirus (COVID-19). Society for Maternal-Fetal Medicine website. Available at: https://www.smfm.org/covid19. Accessed Dec. 28, 2020.
- Considerations for COVID-19 vaccination in lactation. Academy of Breastfeeding Medicine website. Available at: https://abm.memberclicks.net/abm-statement-considerations-for-covid-19-vaccination-in-lactation. Accessed Dec. 28, 2020.
Dr. Niforatos is an emergency medicine resident at the Johns Hopkins School of Medicine in Baltimore and research editor of Brief19.com. Follow him on Twitter @ReverendofDoubt and follow Brief19 @Brief_19.
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