In The Lancet Infectious Diseases, Niklas Bobrovitz and colleagues3 present the results of a well-conducted systematic review and meta-analysis investigating the long-term benefit of SARS-CoV-2 ...vaccines in individuals who have developed hybrid immunity. Several countries still face vaccine shortages, and the benefit of offering multiple booster doses should be discussed in light of the findings of the present study.3 Even though nearly 70% of the world's population has received at least one SARS-CoV-2 vaccine dose, the distribution of vaccine coverage remains unequal. Fiocruz allocates all its manufactured products to the Ministry of Health in Brazil for public health use.
Among people aged 65 years or older, the initially high vaccine effectiveness against hospitalisation provided by three or four doses of monovalent vaccines decreased in the first 6 months, ...plateauing at an effectiveness of roughly 50% up to 14 months after the last dose. Furthermore, in the Canadian Immunization Research Network Study (available only as a preprint),5 protection against hospitalisation was similar in the recipients of monovalent and bivalent boosters—around 80% up to 119 days after the dose. Considering the tremendous inequality in access to COVID-19 vaccine doses—only 30% of people in Africa have received the primary scheme of two doses,11 whereas many high-income countries have offered five doses to some sections of the population—careful cost–benefit analyses are needed.
There is considerable interest in the waning of effectiveness of coronavirus disease 2019 (COVID-19) vaccines and vaccine effectiveness (VE) of booster doses. Using linked national Brazilian ...databases, we undertook a test-negative design study involving almost 14 million people (~16 million tests) to estimate VE of CoronaVac over time and VE of BNT162b2 booster vaccination against RT-PCR-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe COVID-19 outcomes (hospitalization or death). Compared with unvaccinated individuals, CoronaVac VE at 14-30 d after the second dose was 55.0% (95% confidence interval (CI): 54.3-55.7) against confirmed infection and 82.1% (95% CI: 81.4-82.8) against severe outcomes. VE decreased to 34.7% (95% CI: 33.1-36.2) against infection and 72.5% (95% CI: 70.9-74.0) against severe outcomes over 180 d after the second dose. A BNT162b2 booster, 6 months after the second dose of CoronaVac, improved VE against infection to 92.7% (95% CI: 91.0-94.0) and VE against severe outcomes to 97.3% (95% CI: 96.1-98.1) 14-30 d after the booster. Compared with younger age groups, individuals 80 years of age or older had lower protection after the second dose but similar protection after the booster. Our findings support a BNT162b2 booster vaccine dose after two doses of CoronaVac, particularly for the elderly.
Abstract
To date, no information has been published on the effectiveness of inactivated whole-virus COVID-19 vaccines plus heterologous booster against symptomatic infection and severe outcomes ...(hospitalization or death) during the dominance of the SARS-CoV-2 Omicron variant period. We evaluated the vaccine effectiveness (VE) of CoronaVac plus BNT162b2 booster during the period of dominance of the Omicron variant in Brazil (January to April 2022). Using a test-negative design, we analysed data for 2,471,576 individuals tested during the Omicron variant’s dominant period using a nationally linked database from Brazil. Compared to unvaccinated, vaccinees maintained protection against severe outcomes, with an estimated VE of 84.1% (95% CI:83.2–84.9) at more than 120 days after BNT162b2 booster. Furthermore, while we detected a high level of protection against severe outcomes for individuals up to 79 years old, waning was observed for individuals aged ≥80 years, with VE decreasing from 81.3% (95% CI:77.9–84.2) at 31–60 days to 72.9% (95% CI:70.6–75.1) at 120 days or more after the booster dose. However, no significant protection against symptomatic infection was observed at this time period. In conclusion, except for individuals aged ≥80 years, CoronaVac plus a BNT162b2 booster dose offered high and durable protection against severe outcomes due to Omicron.
COVID-19 vaccines have proven highly effective among individuals without a previous SARS-CoV-2 infection, but their effectiveness in preventing symptomatic infection and severe outcomes among ...individuals with previous infection is less clear. We aimed to estimate the effectiveness of four COVID-19 vaccines against symptomatic infection, hospitalisation, and death for individuals with laboratory-confirmed previous SARS-CoV-2 infection.
Using national COVID-19 notification, hospitalisation, and vaccination datasets from Brazil, we did a test-negative, case-control study to assess the effectiveness of four vaccines (CoronaVac Sinovac, ChAdOx1 nCoV-19 AstraZeneca, Ad26.COV2.S Janssen, and BNT162b2 Pfizer-BioNtech) for individuals with laboratory-confirmed previous SARS-CoV-2 infection. We matched cases with RT-PCR positive, symptomatic COVID-19 with up to ten controls with negative RT-PCR tests who presented with symptomatic illnesses, restricting both groups to tests done at least 90 days after an initial infection. We used multivariable conditional logistic regression to compare the odds of test positivity and the odds of hospitalisation or death due to COVID-19, according to vaccination status and time since first or second dose of vaccines.
Between Feb 24, 2020, and Nov 11, 2021, we identified 213 457 individuals who had a subsequent, symptomatic illness with RT-PCR testing done at least 90 days after their initial SARS-CoV-2 infection and after the vaccination programme started. Among these, 30 910 (14·5%) had a positive RT-PCR test consistent with reinfection, and we matched 22 566 of these cases with 145 055 negative RT-PCR tests from 68 426 individuals as controls. Among individuals with previous SARS-CoV-2 infection, vaccine effectiveness against symptomatic infection 14 or more days from vaccine series completion was 39·4% (95% CI 36·1–42·6) for CoronaVac, 56·0% (51·4–60·2) for ChAdOx1 nCoV-19, 44·0% (31·5–54·2) for Ad26.COV2.S, and 64·8% (54·9–72·4) for BNT162b2. For the two-dose vaccine series (CoronaVac, ChAdOx1 nCoV-19, and BNT162b2), effectiveness against symptomatic infection was significantly greater after the second dose than after the first dose. Effectiveness against hospitalisation or death 14 or more days from vaccine series completion was 81·3% (75·3–85·8) for CoronaVac, 89·9% (83·5–93·8) for ChAdOx1 nCoV-19, 57·7% (−2·6 to 82·5) for Ad26.COV2.S, and 89·7% (54·3–97·7) for BNT162b2.
All four vaccines conferred additional protection against symptomatic infections and severe outcomes among individuals with previous SARS-CoV-2 infection. The provision of a full vaccine series to individuals after recovery from COVID-19 might reduce morbidity and mortality.
Brazilian National Research Council, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Oswaldo Cruz Foundation, JBS, Instituto de Salud Carlos III, Spanish Ministry of Science and Innovation, and Generalitat de Catalunya.
...understanding hybrid immunity (ie, immunity derived from infection plus vaccination) is crucial to guide future vaccination policies. Using national databases, we did a test-negative case-control ...study as previously described.1 Cases were defined as individuals with positive RT-PCR or lateral-flow tests and controls as individuals with negative RT-PCT or lateral-flow tests between Jan 1 and March 22, 2022—a period during which omicron was the predominant variant in Brazil (appendix pp 2–4). Fiocruz allocates all its manufactured products to the Ministry of Health for public health use.
Brazil and Scotland have used mRNA boosters in their respective populations since September 2021, with Omicron's emergence accelerating their booster program. Despite this, both countries have ...reported substantial recent increases in Coronavirus Disease 2019 (COVID-19) cases. The duration of the protection conferred by the booster dose against symptomatic Omicron cases and severe outcomes is unclear.
Using a test-negative design, we analyzed national databases to estimate the vaccine effectiveness (VE) of a primary series (with ChAdOx1 or BNT162b2) plus an mRNA vaccine booster (with BNT162b2 or mRNA-1273) against symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and severe COVID-19 outcomes (hospitalization or death) during the period of Omicron dominance in Brazil and Scotland compared to unvaccinated individuals. Additional analyses included stratification by age group (18 to 49, 50 to 64, ≥65). All individuals aged 18 years or older who reported acute respiratory illness symptoms and tested for SARS-CoV-2 infection between January 1, 2022, and April 23, 2022, in Brazil and Scotland were eligible for the study. At 14 to 29 days after the mRNA booster, the VE against symptomatic SARS-CoV-2 infection of ChAdOx1 plus BNT162b2 booster was 51.6%, (95% confidence interval (CI): 51.0, 52.2, p < 0.001) in Brazil and 67.1% (95% CI 65.5, 68.5, p < 0.001) in Scotland. At ≥4 months, protection against symptomatic infection waned to 4.2% (95% CI 0.7, 7.6, p = 0.02) in Brazil and 37.4% (95% CI 33.8, 40.9, p < 0.001) in Scotland. VE against severe outcomes in Brazil was 93.5% (95% CI 93.0, 94.0, p < 0.001) at 14 to 29 days post-booster, decreasing to 82.3% (95% CI 79.7, 84.7, p < 0.001) and 98.3% (95% CI 87.3, 99.8, p < 0.001) to 77.8% (95% CI 51.4, 89.9, p < 0.001) in Scotland for the same periods. Similar results were obtained with the primary series of BNT162b2 plus homologous booster. Potential limitations of this study were that we assumed that all cases included in the analysis were due to the Omicron variant based on the period of dominance and the limited follow-up time since the booster dose.
We observed that mRNA boosters after a primary vaccination course with either mRNA or viral-vector vaccines provided modest, short-lived protection against symptomatic infection with Omicron but substantial and more sustained protection against severe COVID-19 outcomes for at least 3 months.
Exposure to Leishmania induces a humoral immune response that can be used as a marker of parasite exposure.
Herein, ELISA was used to screen sera from patients with Tegumentary Leishmaniasis (TL) ...against different L. infantum-chagasi-derived recombinant proteins (rHSP70, rH2A, rH2B, rH3, rH4 and rKMP11). Among the recombinant proteins, rHSP70 and rH2A showed the best reactivity against human sera obtained from endemic areas of TL. Receiver-Operator Characteristics (ROC) curve analysis was used to identify the effectiveness of these proteins for serodiagnosis of TL. ROC curves confirmed the superior performance of rHSP70 and rH2A, in comparison to the other tested recombinant proteins. Additionally, we evaluated the specificity of the response to rHSP70 and rH2A by testing sera obtained from patients with Chagas' disease, Tuberculosis, Leprosy or Systemic Lupus Erythematosus. In this case, rHSP70 displayed an increased ability to discriminate diseases, in comparison to SLA.
Our results raise possibility of using rHSP70 for the serodiagnosis of TL.
Little is known about vaccine effectiveness over time among adolescents, especially against the SARS-CoV-2 omicron (B.1.1.529) variant. This study assessed the associations between time since ...two-dose vaccination with BNT162b2 and the occurrence of symptomatic SARS-CoV-2 infection and severe COVID-19 among adolescents in Brazil and Scotland.
We did test-negative, case-control studies in adolescents aged 12–17 years with COVID-19-related symptoms in Brazil and Scotland. We linked records of SARS-CoV-2 RT-PCR and antigen tests to national vaccination and clinical records. We excluded tests from individuals who did not have symptoms, were vaccinated before the start of the national vaccination programme, received vaccines other than BNT162b2 or a SARS-CoV-2 booster dose of any kind, or had an interval between their first and second dose of fewer than 21 days. Additionally, we excluded negative SARS-CoV-2 tests recorded within 14 days of a previous negative test, negative tests recorded within 7 days after a positive test, any test done within 90 days after a positive test, and tests with missing sex and location information. Cases (SARS-CoV-2 test-positive adolescents) and controls (test-negative adolescents) were drawn from a sample of individuals in whom tests were collected within 10 days of symptom onset. We estimated the adjusted odds ratio and vaccine effectiveness against symptomatic COVID-19 for both countries and against severe COVID-19 (hospitalisation or death) for Brazil across fortnightly periods.
We analysed 503 776 tests from 2 948 538 adolescents in Brazil between Sept 2, 2021, and April 19, 2022, and 127 168 tests from 404 673 adolescents in Scotland between Aug 6, 2021, and April 19, 2022. Vaccine effectiveness peaked at 14–27 days after the second dose in both countries during both waves, and was significantly lower against symptomatic infection during the omicron-dominant period in Brazil (64·7% 95% CI 63·0–66·3) and in Scotland (82·6% 80·6–84·5), than it was in the delta-dominant period (80·7% 95% CI 77·8–83·3 in Brazil and 92·8% 85·7–96·4 in Scotland). Vaccine efficacy started to decline from 27 days after the second dose for both countries, reducing to 5·9% (95% CI 2·2–9·4) in Brazil and 50·6% (42·7–57·4) in Scotland at 98 days or more during the omicron-dominant period. In Brazil, protection against severe disease remained above 80% from 28 days after the second dose and was 82·7% (95% CI 68·8–90·4) at 98 days or more after receiving the second dose.
We found waning vaccine protection of BNT162b2 against symptomatic COVID-19 infection among adolescents in Brazil and Scotland from 27 days after the second dose. However, protection against severe COVID-19 outcomes remained high at 98 days or more after the second dose in the omicron-dominant period. Booster doses for adolescents need to be considered.
UK Research and Innovation (Medical Research Council), Scottish Government, Health Data Research UK BREATHE Hub, Fiocruz, Fazer o Bem Faz Bem programme, Brazilian National Research Council, and Wellcome Trust.
For the Portuguese translation of the abstract see Supplementary Materials section.
More doses of CoronaVac have been administered worldwide than any other COVID-19 vaccine. However, the effectiveness of COVID-19 inactivated vaccines in pregnant women is still unknown. We estimated ...the vaccine effectiveness (VE) of CoronaVac against symptomatic and severe COVID-19 in pregnant women in Brazil.
We conducted a test-negative design study in all pregnant women aged 18-49 years with COVID-19-related symptoms in Brazil from March 15, 2021, to October 03, 2021, linking records of negative and positive SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) tests to national vaccination records. We also linked records of test-positive cases with notifications of severe, hospitalised or fatal COVID-19. Using logistic regression, we estimated the adjusted odds ratio and VE against symptomatic COVID-19 and against severe COVID-19 by comparing vaccine status in test-negative subjects to test-positive symptomatic cases and severe cases.
Of the 19,838 tested pregnant women, 7424 (37.4%) tested positive for COVID-19 and 588 (7.9%) had severe disease. Only 83% of pregnant women who received the first dose of CoronaVac completed the vaccination scheme. A single dose of the CoronaVac vaccine was not effective at preventing symptomatic COVID-19. The effectiveness of two doses of CoronaVac was 41% (95% CI 27.1-52.2) against symptomatic COVID-19 and 85% (95% CI 59.5-94.8) against severe COVID-19.
A complete regimen of CoronaVac in pregnant women was effective in preventing symptomatic COVID-19 and highly effective against severe illness in a setting that combined high disease burden and marked COVID-19-related maternal deaths.
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