Global diversity of policy, coverage, and demand of COVID-19 vaccines: a descriptive study

Summary Background Hundreds of millions of doses of COVID-19 vaccines have been administered globally, but progress in vaccination varies considerably between countries. We aim to provide an overall picture of COVID-19 vaccination campaigns, including policy, coverage, and demand of COVID-19 vaccines. Methods We conducted a descriptive study of vaccination policy and doses administered data obtained from multiple public sources as of 23 October 2021. We used these data to develop coverage indicators and explore associations of vaccine coverage with socioeconomic and healthcare-related factors. We estimated vaccine demand as numbers of doses required to complete vaccination of target populations of countries according to their national immunization program policies. Findings Use of both mRNA and adenovirus vectored vaccines was the most commonly used COVID-19 vaccines formulary in high-income countries, while adenovirus vectored vaccines were the most widely used vaccines worldwide (176 countries). Almost all countries (98.3%, 173/176) have authorized vaccines for the general public, with 53.4% (94/176) targeting individuals over 12 years and 33.0% (58/176) targeting those ≥18 years. Forty-one and sixty-seven countries have started additional-dose and booster-dose vaccination programs, respectively. Globally, there have been 116.5 doses administered per 100 target population, although with marked inter-region and inter-country heterogeneity. Completed vaccination series coverage ranged from 0% to more than 95.0% of country target populations, and numbers of doses administered ranged from 0 to 239.6 per 100 target population. Doses administered per 100 total population correlated with healthcare access and quality index (R2 = 0.58), socio-demographic index (R2 = 0.56), and GDP per capita (R2 = 0.65). At least 5.54 billion doses will be required to complete interim vaccination programs: 4.65 billion for primary immunization and 0.89 billion for additional/booster programs. Globally, 0.84 and 0.96 dose per individual in the target population are needed for primary immunization and additional/booster programs, respectively. Interpretation There is wide country-level disparity and inequity in COVID-19 vaccines rollout, suggesting large gaps in immunity, especially in low-income countries.

The Effect of Tetanus-Diphtheria-Acellular-Pertussis Immunization During Pregnancy on Infant Antibody Responses: Individual-Participant Data Meta-Analysis

BackgroundImmunization with tetanus-diphtheria-acellular pertussis (Tdap) vaccine in pregnancy is increasingly recommended. We determined the effect of Tdap immunization in pregnancy on infants’ vaccine responses.MethodsIndividual-participant data meta-analysis of ten studies (n=1884) investigating infants’ antibody response to routine immunizations following Tdap immunization in pregnancy was performed. Geometric mean ratios (GMRs) of antigen-specific immunoglobulin G (IgG) levels were calculated using mixed-effects models. Seroprotection rates were compared using chi-squared tests.ResultsInfants of Tdap-immunized women had significantly lower IgG against pertussis toxin (GMR 0.65; 95%CI 0.57-0.74), filamentous haemagglutinin (FHA) (0.68; 0.53-0.87), pertactin (0.65; 0.58-0.72) and fimbria 2/3 (FIM2/3) (0.41; 0.32-0.52) after primary immunization, compared with infants of unimmunized women. These lower levels persisted after booster immunization for FHA (0.72; 0.61-0.84) and FIM2/3 (0.53; 0.29-0.96). After primary immunization, infants of Tdap-immunized women had lower seroprotection rates against diphtheria (90% [843/973] vs 98% [566/579]; p<0.001) and invasive pneumococcal disease (IPD) caused by 5 Streptococcus pneumoniae (SPN) serotypes (SPN5, SPN6B, SPN9V, SPN19A, SPN23F), and higher seroprotection rates against Haemophilus influenzae type b (short-term and long-term seroprotection rates, 86%[471/547] vs 76%[188/247] and 62%[337/547] vs 49%(121/247), respectively, all p=0.001). After booster immunization, seroprotection rates against diphtheria and tetanus were 99% (286/288) and (618/619) in infants of Tdap-immunized women, respectively.ConclusionsInfants of Tdap-immunized women in pregnancy had lower IgG levels against pertussis, diphtheria and some SPN serotypes after their immunization compared with infants of unimmunized women. Enhanced surveillance of pertussis, diphtheria and IPD in infants is needed to determine the clinical significance of these findings.Systematic Review RegistrationCRD42017079171.

A phase IV, multi-centre, randomized clinical trial comparing two pertussis-containing vaccines in pregnant women in England and vaccine responses in their infants

Background Pertussis vaccines containing three or five pertussis antigens are recommended in pregnancy in many countries, but no studies have compared the effect on infants’ antigen-specific immunoglobulin G (IgG) concentrations. The aim of this study was to compare anti-pertussis IgG responses following primary immunization in infants of mothers vaccinated with TdaP5-IPV (low dose diphtheria toxoid, tetanus toxoid, acellular pertussis [five antigens] and inactivated polio) or TdaP3-IPV in pregnancy (three pertussis antigens). Methods This multi-centre phase IV randomized clinical trial was conducted in a tertiary referral centre and primary care sites in England. Women were randomized to receive TdaP5-IPV (n = 77) or TdaP3-IPV (n = 77) at 28–32 gestational weeks. A non-randomized control group of 44 women who had not received a pertussis-containing vaccine in pregnancy and their 47 infants were enrolled post-partum. Results Following infant primary immunization, there was no difference in the geometric mean concentrations (GMCs) of anti-pertussis toxin, filamentous haemagglutinin or pertactin IgG between infants born to women vaccinated with TdaP5-IPV (n = 67) or TdaP3-IPV (n = 63). However, the GMC of anti-pertussis toxin IgG was lower in infants born to TdaP5-IPV- and TdaP3-IPV-vaccinated mothers compared to infants born to unvaccinated mothers (n = 45) (geometric mean ratio 0.71 [0.56–0.90] and 0.78 [0.61–0.98], respectively); by 13 months of age, this difference was no longer observed. Conclusion Blunting of anti-pertussis toxin IgG response following primary immunization occurs in infants born to women vaccinated with TdaP5-IPV and TdaP3-IPV, with no difference between maternal vaccines. The blunting effect had resolved by 13 months of age. These results may be helpful for countries considering which pertussis-containing vaccine to recommend for use in pregnancy. Trial registration ClinicalTrials.gov, NCT02145624, registered 23 May 2014

Role of O-polysaccharide antigen made from B. melitensis in the differential diagnosis of brucellosis in small ruminants

Out of 2942 blood serum samples from small ruminants of 10 flocks with a natural course of brucellosis caused by B. melitensis, 322 samples reacted with both antigens in the RID, of which 90 samples only with the O-PS M antigen (from B. melitensis), only with O-PS A-antigen (from B. abortus) reactive was not revealed. In healthy sheep immunized against brucellosis with the vaccine from strain 19 according to different schemes, only the O-PS M antigen was not found to react. Reaction with O-PS A- and M-antigens was observed in animals that were immunized twice subcutaneously at a dose of 40 billion mc. - after 2 months. after revaccination (60%), as well as in those reimmunized conjunctivally at a dose of 4 billion mc. according to the background of primary immunization subcutaneously at a dose of 40 billion mc. (10%) In animals immunized once or twice conjunctivally, reacting in RID with both antigens was not detected. Out of 2432 blood serum samples of small ruminants, 10 flocks with a brucellosis problem immunized against brucellosis with a vaccine from B.abortus strain 19 according to different schemes, 151 samples (6.2%) reacted positively with both O-PS antigens in RID with both O-PS antigens, of which only 86 samples (56.9%) reacted with O-PS M-antigen. The prevalence of indications of RID with O-PS M-antigen over RID with O-PS A-antigen (O-PS antigen made from Brucellae abortus) in small ruminants in one or another flock is characteristic of infection caused by brucellae melitensis at least in the absence, at least in the presence of the fact of immunization with a vaccine from the B. abortus 19 strain. RID with O-PS M-antigen is an objective indicator of epizootic danger and is able to differentiate brucellosis (B. melitensis) in small ruminants from vaccination-induced reactions (B. abortus 19).

BCG masking phenomena might depend on the species of Mycobacterium

This study investigated BCG masking dependency on the species of Mycobacterium through the immune response to the mycobacterial region of deletion 1 (RD-1) associated growth affecting proteins (GEP).To evaluate the effects of GEP, 8-week old female BALB/c mice were immunized with either the wild type Mycobacterium bovis (MBGEP) or the ATCC Mycobacterium avium subsp. avium (MAGEP) strain and then subjected to further exposure with Mycobacterium terrae or M. avium sub. avium. Mice immunized with MAGEP and those mice further exposed to M. avium subsp. avium had increased granulocytes (GRA) and monocytes to lymphocytes rate (MLR) compared to control mice. Immunization of mice with GEP induced an antibody response one month after primary immunization, as observed by cross-reactivity. Our findings suggest that MAGEP is related to a latent hypersensitivity reaction and an increased risk of mycobacterial infection susceptibility. According to the results of the present study, previous sensitization with NTM antigens results in varying immune reactions after contact with different NTM argued that masking phenomena may be dependent on the species of Mycobacterium.

Long-term Memory Response After a Single Intramuscular Rabies Booster Vaccination 10–24 Years After Primary Immunization

Background Published data regarding long-lasting immunological rabies memory after pre-exposure prophylaxis (PrEP) are scarce. We tested the hypothesis that rabies booster immunization elicits rapid anamnestic responses. Methods For this observational study, we included participants who had received PrEP 10–24 years before inclusion. We measured rabies antibody titers before, and on days 3, 7, and 14 after a single intramuscular booster. Results All 28 participants responded adequately regardless of route of administration or 2-dose vs 3-dose PrEP regimen. Conclusion Rabies immunological memory is reactivated within 7 days after a single intramuscular booster immunization, even when administered 10–24 years after PrEP.

A phase IV, multi-centre, randomized clinical trial comparing two pertussis-containing vaccines in pregnant women in England and vaccine responses in their infants

BackgroundPertussis vaccines containing three or five pertussis antigens are recommended in pregnancy in many countries, but no studies have compared the effect on infants’ antigen-specific immunoglobulin G (IgG) concentrations. The aim of this study was to compare anti-pertussis IgG responses following primary immunization in infants of mothers vaccinated with TdaP5-IPV (low dose diphtheria toxoid, tetanus toxoid, acellular pertussis [five antigens] and inactivated polio) or TdaP3-IPV in pregnancy (three pertussis antigens).MethodsThis multi-centre phase IV randomized clinical trial was conducted in a tertiary referral centre and primary care sites in England from 2014-2016. Women were randomized to receive TdaP5-IPV (n=77) or TdaP3-IPV (n=77) at 28-32 gestational weeks. A non-randomized control group of 44 women who had not received a pertussis-containing vaccine in pregnancy and their 47 infants were enrolled postpartum.ResultsFollowing infant primary immunization, there was no difference in the geometric mean concentrations (GMCs) of anti-pertussis toxin, filamentous haemagglutinin or pertactin IgG between infants born to women vaccinated with TdaP5-IPV (n=67) or TdaP3-IPV (n=63). However, the GMC of anti-pertussis toxin IgG was lower in infants born to TdaP5-IPV and TdaP3-IPV vaccinated mothers compared to infants born to unvaccinated mothers (n=45) (geometric mean ratio: 0.71 [0.56-0.90] and 0.78 [0.61-0.98], respectively); by 13 months of age, this difference was no longer observed.ConclusionBlunting of anti-pertussis toxin IgG response following primary immunization occurs in infants born to women vaccinated with TdaP5-IPV and TdaP3-IPV, with no difference between maternal vaccines. The blunting effect had resolved by 13 months of age. These results may be helpful for countries considering which pertussis-containing vaccine to recommend for use in pregnancy.Clinical Trials identifierClinicalTrials.gov: NCT02145624