AstraZeneca: Vaxzevria

Characteristics of COVID-19 Vaccines in Relation to Pregnancy and Lactation

Active ingredient

Recombinant DNA encoding the SARS-CoV-2 viral spike (S) glycoprotein

Delivery vehicle

Replication-defective chimpanzee adenovirus

Method of administration

Deltoid IM injection

Recommended schedule

2 injections 4-12 weeks apart (WHO, as of Aug 3, 2021). Dosing intervals from 8-12 weeks have been associated with increased, longer- lasting efficacy. As of early August 2021, due to the Delta variant outbreak, discussion centers on whether the second dose should be administered within 4-8 weeks, due to the short-term benefit of being fully immunized sooner outweighing the long-term benefit of the longer interval. As of mid August, 2021, some countries have begun administering a third dose to individuals considered to be at risk. Qualification for a third dose varies between countries, but generally they include older age and factors that may decrease the immune response to the first two doses, such as being an organ transplant recipient.

Dosage per shot

Adult: 0.5 mL

Ages

18 years and older (As of Aug 3, 2021)

Efficacy

74.5% against the Alpha variant and 67.0% against the Delta variant, the latter being greater than the efficacy of this vaccine against the Beta variant. For variants earlier than the Delta, studies have noted higher efficacy in the higher age groups (>/=65 years). Data from Public Health England (PHE) show efficacy ~92% against hospitalization and severe disease caused by the Delta variant and 86% against hospitalization and severe disease caused by the Alpha variant.

PREGNANCY & LACTATION

Recommended “if the benefit of vaccinating a pregnant woman outweighs the potential vaccine risks” (WHO). Currently, the benefits of COVID-19 vaccination, by any of the approved vaccines, far outweigh potential risks both in pregnancy and lactation. However, globally, there is an abundance of policies and philosophies surrounding to what degree potential vaccine recipients should be able to assess the risk vs benefits on their own. There is no plausible mechanism supporting notions that this vaccine, or any of the approved COVID-19 vaccines, might present a particular danger during pregnancy or lactation. Maternal vaccination against SARS-CoV2 may possibly protect newborns and nursing infants against endemic variants of SARS-CoV2, including the Delta variant, while pregnancy is a risk factor for the development of severe COVID- 19 in unvaccinated women and for preterm birth.

Adverse effects

Injection site : pain, erythema, swelling at injection site.

Systemic : fatigue, malaise, headache, myalgia, chills, fever, nausea, arthralgia, diarrhea.

As of August, 2021, studies are underway to determine whether there is a causative relationship between AZD1222 and a scattering of reported cases of thrombotic events, both arterial and venous. The latter, which amount to a very small number of cases, include central venous thrombosis and cerebral venous sinus thrombosis with a heparin-induced thrombocytopenia (HIT)-like syndrome.

Pregnancy and Lactation Positions by Country for the AstraZeneca Vaccine (Vaxzevria)

Sources

Clinical Trials Arena (Public Health England). AstraZeneca’s Covid-19 vaccine shows effectiveness against Delta variant Accessed August 3, 2021

European Medicines Agency. Vaxzevria (previously COVID-19 Vaccine AstraZeneca). Accessed October 1, 2021.

Lopez Bernal J, Andrews N, Gower C, et al. Effectiveness of Covid-19 vaccines against the B.1.617.2 (delta) variant. N Engl J Med. DOI: 10.1056/NEJMoa2108891.

Smadja DM, Yue QY, Chocron R, Sanchez O, Lillo-Le Louet A. Vaccination against COVID-19: insight from arterial and venous thrombosis occurrence using data from VigiBase. Eur Respir J. 2021 Jul; 58(1): 2100956.

Society of Obstetricians and Gynaecologists of Canada. Statement on COVID-19 Vaccination in Pregnancy. Accessed August 3, 2021

Wall EC, Wu M, Harvey R et al. AZD1222-induced neutralising antibody activity against SARS-CoV-2 Delta VOC. Lancet. 2021 Jul 17;398(10296):207-209. doi: 10.1016/S0140-6736(21)01462-8. Epub 2021 Jun 28. PMID: 34197809; PMCID: PMC8238446.

World Health Organization. The Oxford/AstraZeneca COVID-19 vaccine: what you need to know. Accessed August 3, 2021