key: cord-0860605-ip83su2c authors: Ghazvini, Kiarash; Keikha, Masoud title: SARS CoV2 mRNA vaccines: Prolonged dosing intervals and anti-SARS-CoV-2 immunity status date: 2022-03-09 journal: Vacunas DOI: 10.1016/j.vacun.2022.03.001 sha: bce377bddeee68f5409c420bbae582c84333f20c doc_id: 860605 cord_uid: ip83su2c nan The global number of cases infected with SARS-CoV-2 surpassed 433 million as well as 5.94 million deaths on 26 February 2022 (http://covid19.who.int). The mass vaccination is considered as the best strategy to fight with COVID-19 pandemic. However, immune system responses wane after vaccination. Furthermore, the durability of effective immune responses was varied among immunized individuals. Recent evidences suggested the effectiveness of ChAdOx1 (AstraZeneca) adenoviral as well as other non-replicating vaccines by increasing dosing intervals (1) . However, the magnitude and resilience of vaccine-induced immunity remains unclear particularly among mRNA vaccines (2) . Currently, regular schedule dosing intervals for BNT162b2 (Pfizer) and mRNA-1273 (Moderna) vaccines are 21 and 28 days, respectively (3). We provide a comprehensive literature search by ISI Web of Science, PubMed, and Scopus to demonstrate the SARS-CoV-2 antibody status after extended mRNA vaccine dosing intervals. Firstly, Brockman et al. investigated humoral immune responses after one-month following one dose of the BNT162b2 mRNA COVID-19 vaccine in healthcare facilities. They found that after 30 days, the spike protein receptor binding domain (S/RBD) antibody titers were 4-fold lower than seronegative healthcare workers (HCW); However, convalescent HCW exhibited 7-to 20fold higher levels of binding antibodies to neutralize live virus (4). Grunau This fact was assessed by Robinson et al., who compared the anti-spike protein neutralizing antibody concentration in healthy individuals as well as in cancer patients following BNT162b2, AZD1222, and mRNA-1273 administered at extended dosing intervals. The resuts showed a mean serum anti-spike protein antibody level was 382.4 BAU/ml (binding antibody unit) for control patients, 265.8 BAU/ml for solid cancer patients, and 168.2 BAU/mL in hematological cancer patients (8) . Regarding effectiveness of extended mRNAvaccine dosing intervals with respect to various SARS-CoV-2 variants, another study, Grunau et al. revealed that a 100-120 days mRNA SARS-CoV-2 vaccine dosing intervals using BNT162b2 and mRNA-1273 can induce a significant immune response against the Wuhan, Beta, Gamma and Delta variants (9) . In summary, extended mRNA-vaccine dosing intervals could better stimulate a robust immune response against circulating SARS-CoV-2 variants. The second dosage intervals of the Pfizer/BioNTech BNT162b2 and Oxford/AstraZeneca was changed in the United Kingdom on December 31, 2020. Thus, optimizing mRNA vaccine dosage intervals can have influenced mRNA based-vaccine effectiveness against SARS-CoV-2 infection. Single-dose administration and the influence of the timing of the booster dose on immunogenicity and efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine: a pooled analysis of four randomised trials A preliminary report of a randomized controlled phase 2 trial of the safety and immunogenicity of mRNA-1273 SARS-CoV-2 vaccine SARS-CoV-2 B. 1.1. 529 (Omicron) Variant-United States Weak humoral immune reactivity among residents of long-term care facilities following one dose of the BNT162b2 mRNA COVID-19 vaccine A Higher Antibody Response Is Generated with a 6-to 7-Week (vs Standard) Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccine Dosing Interval Immunogenicity of standard and extended dosing intervals of BNT162b2 mRNA vaccine Strong humoral immune responses against SARSCoV-2 Spike after BNT162b2 mRNA vaccination with a 16-week interval between doses Quantitative Analysis of SARS-CoV-2 Antibody Status between Patients with Cancer and Healthy Individuals with Extended Vaccination Dosing Intervals in Canada Immunogenicity of extended mRNA SARS-CoV-2 vaccine dosing intervals The authors have no conflict of interest.