ABSTRACT
Background: The COVID-19 vaccine candidate CVnCoV comprises sequence-optimized mRNA encoding SARS-CoV-2 S-protein encapsulated in lipid nanoparticles. In this phase 2a study, we assessed reactogenicity and immunogenicity of two or three doses in younger and older adults. Methods: Younger (18-60 years) and older (>60 years) adults were enrolled in two sites in Panama and Peru to receive either 6 or 12 µg doses of CVnCoV or licensed control vaccines 28 days apart; subsets received a 12 µg booster dose on Day 57 or Day 180. Solicited adverse events (AE) were reported for 7 days and unsolicited AEs for 4 weeks after each vaccination, and serious AEs (SAE) throughout the study. Humoral immunogenicity was measured as neutralizing and receptor binding domain (RBD) IgG antibodies and cellular immunogenicity was assessed as CD4+/CD8 + T cell responses. Results: A total of 668 participants were vaccinated (332 aged 18-60 years and 336 aged > 60 years) including 75 who received homologous booster doses. Vaccination was well tolerated with no vaccine-related SAEs. Solicited and unsolicited AEs were mainly mild to moderate and resolved spontaneously. Both age groups demonstrated robust immune responses as neutralizing antibodies or RBD-binding IgG, after two doses, with lower titers in the older age group than the younger adults. Neither group achieved levels observed in human convalescent sera (HCS), but did equal or surpass HCS levels following homologous booster doses. Following CVnCoV vaccination, robust SARS-CoV-2 S-protein-specific CD4 + T-cell responses were observed in both age groups with CD8 + T-cell responses in some individuals, consistent with observations in convalescing COVID-19 patients after natural infection. Conclusions: We confirmed that two 12 µg doses of CVnCoV had an acceptable safety profile, and induced robust immune responses. Marked humoral immune responses to homologous boosters suggest two doses had induced immune memory.
ABSTRACT
Background: There is no evidence to date on immunogenic response among individuals who participated in clinical trials of COVID-19 experimental vaccines redirected to standard national vaccination regimens. Methods: This multicentre, prospective controlled cohort study included subjects who received a COVID-19 experimental vaccine (CVnCoV)(test group, TG) - and unvaccinated subjects (control group, CG), selected among individuals to be vaccinated according to the Spanish vaccination program. All study subjects received BNT162b2 as a standard national vaccination schedule, except 8 (from CG) who received mRNA-1273 and were excluded from immunogenicity analyses. Anti-RBD antibodies level and neutralising titres (NT50) against G614, Beta, Mu, Delta and Omicron variants were analysed. Reactogenicity was also assessed. Findings: 130 participants (TG:92; CG:38) completed standard vaccination. In TG, median (IQR) of anti-RBD antibodies after first BNT162b2 dose were 10740·0 BAU/mL (4466·0-12500) compared to 29·8 BAU/mL (14·5-47·8) in CG (p <0·0001). Median NT50 (IQR) of G614 was 2674·0 (1865·0-3997·0) in TG and 63·0 (16·0-123·1) in CG (p <0·0001). After second BNT162b2 dose, anti-RBD levels increased to ≥12500 BAU/mL (11625·0-12500) in TG compared to 1859·0 BAU/mL (915·4-3820·0) in CG (p <0·0001). NT50 was 2626·5 (1756·0-5472·0) and 850·4 (525·1-1608·0), respectively (p <0·0001). Variant-specific (Beta, Mu, Omicron) response was also assessed. Most frequent adverse reactions were headache, myalgia, and local pain. No severe AEs were reported. Interpretation: Heterologous BNT162b2 as third and fourth doses in previously suboptimal immunized individuals elicit stronger immune response than that obtained with two doses of BNT162b2. This apparent benefit was also observed in variant-specific response. No safety concerns arose. Funding: Partly funded by the Institute of Health Carlos-III and COVID-19 Fund, co-financed by the European Regional Development Fund (FEDER) "A way to make Europe".
ABSTRACT
Coronavirus disease 2019 (COVID-19) vaccines proved a strong clinical efficacy against symptomatic or moderate/severe COVID-19 and are considered the most promising approach for curbing the pandemic. However, some questions regarding the safety of COVID-19 vaccines have been recently raised. Among adverse events to vaccines and despite a lack of signal during phase III clinical trials, an increase in blood pressure (BP) after COVID-19 vaccination has been reported as a potential adverse reaction. We systematically analyze this topic and undertook a meta-analysis of available data to estimate the proportion of patients with abnormal BP or raise in BP after vaccination. Six studies entered the final analysis. Overall, studies accrued 357,387 subjects with 13,444 events of abnormal or increased BP. After exclusion of outlier studies, the pooled estimated proportion of abnormal/increased BP after vaccination was 3.20% (95% CI: 1.62-6.21). Proportions of cases of stage III hypertension or hypertensive urgencies and emergencies was 0.6% (95% CI: 0.1% to 5.1%). In conclusion, abnormal BP is not rare after COVID-19 vaccination, but the basic mechanisms of this phenomenon are still unclear and require further research.