BNT162b2

No neutralization of Omicron was observed in subjects vaccinated with two doses 6 months after the second immunization, but the third booster dose of BNT16b2 neutralized Omicron. Three months after booster dose, the neutralization weakened. 

In convalescent and vaccinated individuals, the capacity of sera to neutralize Omicron variant of SARS-CoV-2 was decreased only moderately, compared to the D614G strain. 

Although still capable of neutralization, the sera of vaccinated individuals displayed a several-fold lower neutralization capacity against the Omicron variants BA.1 and BA.2 in vitro. 

Compared to an ancestral strain, the neutralization of SARS-CoV-2 Omicron variants BA.1, BA.1.1, or BA.2 by sera of vaccinated individuals was detectable, yet s weaker. 

The sera of the majority of individuals who were previously vaccinated with Ad26.COV2.S and have recently received a booster dose of an mRNA vaccine were capable of Delta and Omicron variants’ (pseudoviruses’) neutralization in vitro. Administration of a third vaccine dose substantially increased neutralization of SARS-CoV-2 pseudovirus by sera of vaccinated individuals. A two-dose vaccination regimen did not provide a high level of protection against newly emerging variants, especially Omicron. The neutralization was generally less potent against the Delta variant and even less potent against the Omicron variant, compared to the wild type. Previous infection mostly increased neutralization even in individuals without a booster. The antibody protection decreased with time past from the vaccination. Sample size: 21 (recent vaccination) + 33 (distant vaccination) + 27 (convalescent and distant vaccination) + 30 (with a booster). Main outcome: 2 or 3 doses.

Although the capacity of sera of vaccinated individuals markedly decreased for the omicron strain after a two-dose regimen, a third (booster) vaccination significantly increased omicron neutralization in vitro. 

Although having reduced efficiency, sera obtained from individuals who had received 3 doses of the vaccine were capable to neutralize the Omicron variant of SARS-CoV-2 in vitro. 

The sera of most of the vaccinated individuals retained some neutralization capacity against SARS-CoV-2 Omicron Spike-pseudotyped virus in vitro. The neutralization titres were severalfold lower, however. A comparatively smaller decrease in efficacy was observed in the case of three-dose regimen (in dialysis patients) or in convalescent patients who had received two doses of the vaccine. 

In the cohort of immunocompromised patients, vaccination was generally safe (there was one fatal putative adverse reaction, however). Seroconversion in the test cohort (72.2%) was lower compared to the control (especially in the case of solid organ transplantation patients and chronic lymphocytic leukaemia patients). These results support additional booster doses in immunocompromised individuals. Sample size: 449 + 90 control. Dosage: Regular scheme. Main outcome: Seroconversion rate two weeks after the second dose.

Circulatory exosomes carrying SARS-CoV-2 Spike protein on their surface were detected in vaccinated healthy individuals. The exosomes were immunogenic in mice. Dosage: Two-dose regimen. 

The mRNA vaccination induced an immune response in most of the CAR T cell therapy (targeting B cell antigens) recipients. Spike-specific antibody levels were dependent on patients’ circulating B cell counts, but CD4 T cell responses were noted even in some patients with severe B cell depletion. Sample size: 6 + 7 healthy control. Dosage: 2-dose regimen. 

BNT2b2 vaccine-elicited serum was more effective against B.1. as against the variants Kappa, Delta or Epsilon. 

There was a decrease of neutralization capacity of sera of vaccinated individuals associated with the Delta variant of SARS-CoV-2. Most of the samples (after a two-dose vaccination regimen) were still able to neutralize the virus in vitro, however. 

The sera of vaccinated individuals retained some neutralization capacity against SARS-CoV-2 pseudoviruses (various variants including Alpha and Beta) in vitro. 

The Pfizer-BioNTech vaccine was 88% effective against symptomatic disease from the B.1.617.2 variant 2 weeks after the second dose, compared to 93% effectiveness against the B.1.1.7 variant.

A single vaccine dose in subjects with COVID-19 infection history elicited potent T cell and B cell responses against SARS-CoV-2 variants B.1.1.7. and B.1.351. The single dose regimen elicited significantly weaker responses in infection-naïve subjects. Sample size: Sera of vaccinated (non)convalescent subjects. Dosage: A single dose.

The seroconversion rate in cancer patients was lower compared to healthy controls. It was especially low after single-dose vaccination but was improved by boosting. Cancer patients were therefore suggested to be prioritized for the two-dose regimen with 21 days between the doses. Sample size: 151 + 54 healthy controls. Dosage: Single-dose or two-dose regimen. Primary outcome: Seroconversion.

Majority of haemodialysis patients who received two vaccine doses three weeks apart developed a high antibody response. The response was slightly weaker in the elderly patients. No response was observed in the patients undergoing chemotherapy and under active immunosuppression. Sample size: 326. Dosage: Standard two-dose regimen.

A significant negative correlation was observed between the number of positive COVID-19 PCR tests and proportion of vaccinated individuals among health care workers. Dosage: A single dose.

The effectiveness of the vaccine against both symptomatic and asymptomatic infections was calculated to be 70% 3 weeks after first dose administration and 85% 1 week after the second one. Sample size: 15,121 without previous infection (of which 1,405 not vaccinated) + 8,203 with previous infection (of which 1,278 not vaccinated). Dosage: Standard regimen.

Combined with active surveillance programme, the vaccination was effective in suppressing infection spread in the cohort of nursing home residents even after B.1.1.7. strain introduction. Sample size: 292,268 RT-PCR specimens (of which 200,293 from nursing homes).

In the studied cohort, the vaccine displayed efficacy in eliciting an antibody response and was generally safe. Sample size: 122 (haemodialysis) + 23 (peritoneal dialysis). Dosage: Standard regimen.

The vaccination induced anti-RBD (SARS-CoV-2 Spike) IgG and neutralizing antibody responses in the subjects. The responses were lower in elderly, especially in male subjects, which underscores the need of administration of two doses. Sample size: 255 healthcare workers + 112 elderly volunteers. Dosage: Standard regimen. Primary outcome: Anti-RBD binding IgG and neutralizing antibody levels.

Analysis pooled with

A 4-fold reduction in asymptomatic SARS-CoV-2 infection rate was observed ≥12 days after the administration of the first vaccine dose. Sample size: Ca. 9000 (with approximately equal numbers of vaccinated and non-vaccinated subjects). Dosage: A single dose.

The antibody levels in haemodialysis patients (HDPs) under 60 years of age were comparable to the control group. Lower antibody titres were observed in older HDPs, however. Sample size: 72 + 16 control (vaccinated healthcare workers). Dosage: Two standard doses, 4 weeks apart. Primary outcome: anti-SARS-CoV-2 IgGs.

Although the neutralizing titres against the B.1.351 variant of SARS-CoV-2 were lower compared to other tested common strains, a single vaccine dose induced neutralizing antibody titres which were significantly higher than the titres measured prior to vaccination. Sample size: 6 donors. Dosage: A single dose.

Vaccination elicited CD4+ T cell response which might effectively recognize some of the common SARS-CoV-2 variants.

Maternal and cord blood was positive for anti-S and anti-RBD (SARS-CoV-2 Spike) IgGs, suggesting possible maternal and neonatal protection from SARS-CoV-2 infection. Sample size: 20 sera donors. Vaccine dosage: Standard regimen.

(Analyses pooled with

After a single dose administration, individuals with past SARS-CoV-2 infection developed anti-Spike IgG levels and capacity to inhibit ACE2-binding similar to those without previous SARS-CoV-2 infection after two doses. Sample size: 1,090 (of which 35 were infected in the past and received a single vaccine dose and 228 were not previously infected and received two vaccine doses). Dosage: One or two standard doses.

No viral RNA was detectable in the murine lung tissue after SARS-CoV-2 viral challenge. The immunization also alleviated pathological histological changes.

Anti-S1/S2 (SARS-CoV-2 Spike) IgG levels in COVID-19 convalescent individuals 14 days post immunization were similar to the levels detected in infection-naïve subjects 14 days post second vaccine dose administration. Sample size: 12 convalescent donors + 54 infection-naïve donors. Dosage: Standard regimen.

There was a decrease of neutralization capacity of sera of vaccinated individuals associated with emerging variants of concern. Most of the samples were still able to neutralize the variants tested in vitro, however. 

A significant reduction in the mean viral loads was noted in vaccinated individuals who got infected with SARS-CoV-2. The reduction was observed starting on day 12 post 1st dose administration. These results suggest reduced infectivity even in the vaccinated individuals positive for SARS-CoV-2.
Sample size: 4,938. Dosage: Two standard doses (analyses beginning with the 1st dose administration). Primary outcome: Average RT-PCR Ct values.

Two weeks after the first vaccine dose administration, increased anti-Spike (SARS-CoV-2) IgA titres were observed in breast milk. Although decline was noted 40+ days after the first dose (therefore, after the second dose administration), the titres were still high above baseline. Similarly, IgG anti-Spike titres were elevated in breast milk, but antibody titres for this class did not decline within the observation period. Sample size: 5 donors. Dosage: Standard vaccination regimen.

The mean viral load as measured by RT-PCR on a nasopharyngeal swab sample in asymptomatic COVID-19 patients vaccinated with a single dose 12–15 days prior to the virus detection was 2.4-fold lower compared to asymptomatic non-vaccinated patients. The vaccination was therefore hypothesized to lower transmissibility of the virus even in positive (asymptomatic) individuals. Sample size: 5 + 5 control (SARS-CoV-2 positive). Dosage: All cases detected after a single immunization. Primary outcome: Nasopharyngeal viral load.

A difference in neutralizing capacity of antibodies from sera of vaccinated mice, non-human primates, and human subjects against SARS-CoV-2 D614 and G614 was detectable, but the difference was only modest.

(Data pooled with those for

The vaccine was safe and elicited an immune response in elderly nursing home residents. The antibody titres were higher in those with previous COVID-19 infection. The vaccine is suggested for use irrespective of frailty and disability profiles. Sample size: 134. Dosage: 2 regular doses.

COVID-19 mRNA vaccines generated robust humoral immunity in pregnant and lactating women, with immunogenicity and reactogenicity similar to that observed in non-pregnant women. Vaccine-induced immune responses were significantly greater than the response to natural infection. Immune transfer to neonates occurred via placenta and breastmilk.

A pooled analysis with

(Analyses pooled with

During the vaccination campaign, a marked decrease of COVID-19 incidence among healthcare workers was observed, which contrasts with epidemiologic data in general population. The decrease seems to be temporally correlated with the progress of the vaccination campaign among the healthcare workers. Sample size: 6680. Dosage: Standard two-dose regimen.

3 weeks after a single dose administration, the subjects without history of SARS-CoV-2 infection displayed significant increase in anti-S1, anti-S2, and anti-RBD (of Spike protein) antibody titres, yet the titres were lower compered to the subject with recently (30–60 days before vaccination) laboratory-confirmed infection or those with prior antibody levels indicating positive infection history. The anti-nucleocapsid antibody levels were not changed by the vaccination, which is in line with the vaccine design (encoded modified Spike protein serving as the immunogen). Sample size: 152 without past confirmed SARS-CoV-2 infection (6 of which with possible undiagnosed infection) + 36 with confirmed past SARS-CoV-2 infection. Dosage: A single dose. Primary outcome: Antibody responses.

(Data pooled with

The sera of most of the vaccinated individuals manifested decreased neutralizing activity against SARS-CoV-2 Spike B.1.351 and P.1 variants. This indicates that the vaccine might provide less robust protection from the infection by viruses of the corresponding strains. The neutralizing capacity at lower tested serum dilutions was present and provided complete neutralization, however. The neutralization of B.1.1.7 was reduced only slightly.

SARS-CoV-2 Spike protein of some strains, especially of B.1.351 (“South Africa”), seems to be several-fold more resistant to neutralization by antibodies from vaccinated subjects compared to the wild type virus. This is especially true for individuals with a single dose vaccination without prior SARS-CoV-2 infection or exposure. The sera of subjects vaccinated with two doses, or of those with previous virus exposure, seem to retain neutralizing capacity to some extent, however.

Sera of vaccinated older adults included antibodies which retained their neutralizing capacity against SARS-CoV-2 Spike protein variant B.1.1.7 and K417N, E484K, and N501Y triple mutant. However, some decrease in neutralization capacity of the sera against the B.1.1.7 variant was observed. Alarmingly, the neutralizing capacity against the triple mutant was decreased or completely diminished in several antibodies.

While the neutralizing antibody titres after a single vaccine dose in adults with no COVID-19 infection history did not significantly increase after a single dose administration, the increase in titres of previously infected individuals was statistically and numerically significant. Sample size: 52 (COVID-19-naïve) + 69 (with COVID-19 history). Dosage: A singe dose.

In individuals who have been infected with SARS-CoV-2 in the past a single dose of the vaccine elicited after 7 days anti-RBD IgG and neutralizing antibody responses similar to the responses in infection-naïve individuals 7 days after the second dose administration. Sample size: 5 with COVID-19 infection history + 9 infection-naïve.

At days 7 or 14 after a single-dose vaccination, the health-care workers with prior SARS-CoV-2 infection developed higher anti-Spike antibodies and more potent live virus neutralizing capacity compared to the non-infected subjects. Sample size: 13 with evidence of previous symptomatic SARS-CoV-2 infection + 6 with evidence of previous asymptomatic SARS-CoV-2 infection + 10 seronegative. Data were pooled with

Individuals vaccinated with a single dose had similar levels of anti-Spike (SARS-CoV-2) antibodies to the ones with previous SARS-CoV-2 infection (mild or asymptomatic). Subjects who recovered from SARS-CoV-2 infection and received a single dose of the vaccine had significantly higher anti-Spike titres. Sample size: 24 with evidence of previous SARS-CoV-2 infection + 27 seronegative. Dosage: A single dose. Primary outcome: Immunological response 19–29 (median 22) days post single-dose vaccination.

Based on T cell responses, anti-Spike protein antibody titres, and neutralizing antibody titres, it was concluded that individuals who recovered from SARS-CoV-2 infection before administration of the vaccine produced significant immunological response after a single-dose administration. On the other hand, a single vaccination might be insufficient for protection against COVID-19 in some individuals, especially over 50 years of age, who were not infected prior to the vaccination. Sample size: 21 with evidence of previous SARS-CoV-2 infection + 51 infection-naïve. Dosage: A single dose. Primary outcome: Immunological response 21-25 days post single-dose vaccination.

The effectivity of the vaccine 14 to 20 days after the first dose administration in preventing documented infection, symptomatic COVID-19, hospitalization, and severe disease was observed to be ca. 46%, 57%, 74%, and 62% respectively. The values at 7 or more days after the second dose were 92%, 94%, 87%, and 92%, respectively. The effectiveness in preventing COVID-19-caused death was estimated to be 72% for days 14 to 20 after the first immunization and 84% at the period starting 7 days after the second dose. Sample size: 596,618 matched pairs.

Neutralization titres against the Beta strain of SARS-CoV-2 were significantly lower compared to the original strain. A majority of samples still neutralized the virus, however. 

Although a 3.3-fold decrease in neutralization titres against B.1.1.7 strain was observed compared to an early Wuhan-related strain, the neutralization remained robust, and no evidence of vaccine escape was observed.

The infection rate reduction in vaccinated healthcare workers was 30% 1-14 days after the first dose and 75% 15-28 days after the first dose (with 91% of the subjects receiving the second dose on day 21 or 22). Symptomatic infection rate reduction values were 47% and 85% at these time intervals, respectively. Sample size: 7,214 received the first dose of which 6,037 received the second one + 1,895 non-vaccinated.

Sera from vaccinated individuals were capable of B.1.1.7 strain neutralization in vitro, despite a modest decrease in neutralization capacity compared to the Victoria strain. 

Some of the antibodies identified in the B cells from immunized volunteers which bound SARS-CoV-2 Spike S or BRD domain of the original SARS-CoV-2 were found to have a decreased or no neutralizing activity against some of the emerging Spike variants (E484K or N501Y or the K417N:E484K:N501Y combination). Overall, the plasma neutralizing activity against these variants was present but decreased.

The differences between neutralization titres in sera from vaccinated humans (2 or 4 weeks after the 2nd dose) against modified live SARS-CoV-2 viruses carrying common Spike mutations and titres against the non-mutated form were of a moderate magnitude only (0.81- to 1.41-fold). The lowest value was observed for the E484K + N501Y + D614G combination, which corresponds to the mutations in the so-called

A single intramuscular dose elicited a strong immune response in mice characterized by a potent TH1 response, prevalent IFNγ-producing CD8+ T-cell response, and higher presence of germinal centre B cells in injection site draining lymph nodes and spleen. Vaccination of rhesus macaques using a prime/boost scheme resulted in SARS-CoV-2 neutralising geometric mean titres 8.2 to 18.2 more potent than those of convalescent COVID-19 patients’ sera. The macaques were protected from viral RNA presence in the lower respiratory tract. No vaccine-induced disease enhancement was observed.

vaccination with BNT162b2 at well tolerated doses elicits a combined adaptive humoral and cellular immune response, which together may contribute to protection against COVID-19

The vaccine displayed 95% efficacy in preventing COVID-19 infection with similar outcomes in all analysed subgroups. The incidence of severe adverse reactions was low and comparable with the placebo group. Sample size: 21,720 +21,728 placebo. Dosage: Two doses of 30 μg 21 days apart.

The vaccination was safe and led to seroconversion in some of the patients. The rate of seroconversion in the CAR T cell therapy recipients was lower compared to the healthy control, however. Sample size: 23 + 25 control. Dosage: 2-dose regimen.