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The Costa Rica Vaccine Trial (CVT), a phase III randomized clinical trial, provided the initial data that one dose of the HPV vaccine could provide durable protection against HPV infection. Although the study design was to administer all participants three doses of HPV or control vaccine, 20% of women did not receive the three-dose regimens, mostly due to involuntary reasons unrelated to vaccination. In 2011, we reported that a single dose of the bivalent HPV vaccine could be as efficacious as three doses of the vaccine using the endpoint of persistent HPV infection accumulated over the first four years of the trial; findings independently confirmed in the GSK-sponsored PATRICIA trial. Antibody levels after one dose, although lower than levels elicited by three doses, were 9-times higher than levels elicited by natural infection. Importantly, levels remained essentially constant over at least seven years, suggesting that the observed protection provided by a single dose might be durable. Much work has been done to assure these non-randomized findings are valid. Yet, the group of recipients who received one dose of the bivalent HPV vaccine in the CVT and PATRICIA trials was small and not randomly selected nor blinded to the number of doses received. The next phase of research is to conduct a formal randomized, controlled trial to evaluate the protection afforded by a single dose of HPV vaccine. Complementary studies are in progress to bridge our findings to other populations, and to further document the long-term durability of antibody response following a single dose.

Background. Live oral rotavirus (RV) vaccines have shown modest efficacy among children in African countries for reasons that are not completely understood. We examined the possible inhibitory effect of preexisting antirotavirus antibodies on immunogenicity of monovalent RV vaccine (RV1). Methods. Mother–infant pairs were enrolled at presentation for their routine immunization visit in Soweto, South Africa, when infants were aged 5–8 weeks. Infant serum samples were obtained before the first and second doses of RV1 and 1 month after the second dose. Maternal serum and breast milk samples were obtained prior to administration of each dose of RV1 to infants. RV-specific immunoglobulin G (IgG), IgA, and neutralizing activity in sera of infants and serum or breast milk samples of mothers were measured using enzyme-linked immunosorbent assays or a microneutralization test. Results. Of the 107 serum pairs from infants who were seronegative for RV IgA at enrollment, we observed a strong positive association between IgG titers in pre-dose 1 sera of infants and mothers and significant negative associations between IgG titers in pre-dose 1 sera of infants and seroconversion to RV1 post-dose 1. Similarly, mothers whose infants' IgA seroconverted after RV1 had significantly lower pre-dose 1 IgG titers in sera than those whose infants did not seroconvert. Conclusions. High levels of preexisting serum IgG, including transplacentally acquired maternal IgG, appeared to have an inhibitory effect on the immunogenicity of RV1 among infants and may, in part, contribute to lower efficacy of RV vaccines in this and other low-income settings.

► Two distinct lineages of influenza B virus co-circulate annually. ► The B lineage chosen for TIV is often not the B lineage that circulates. ► QIV contains two influenza B strains, one from each lineage. ► QIV was as safe and immunogenic as licensed TIV in adults. ► QIV should offer protection against both B lineages simultaneously. To evaluate the safety and immunogenicity of a prototype quadrivalent inactivated influenza vaccine (QIV) containing two influenza B strains, one of each lineage, compared with licensed trivalent inactivated influenza vaccines (TIVs) containing either a Victoria B-lineage strain (2009–2010 TIV) or a Yamagata B-lineage strain (2008–2009 TIV). Healthy adults ≥18 years of age were eligible to participate in this phase II, open-label, randomized, controlled, multicenter study conducted in the US. Participants received a single dose of 2009–2010 TIV, 2008–2009 TIV, or QIV. Sera were collected before and 21 days after vaccine administration to test for hemagglutination inhibition (HAI) antibodies to each of the four influenza strains. Immunogenicity endpoints included geometric mean HAI antibody titers (GMTs) and rates of seroprotection (titer ≥1:40) and seroconversion (4-fold rise pre- to post-vaccination). Safety endpoints included frequency of solicited injection-site and systemic reactions occurring within 3 days of vaccination, and unsolicited non-serious adverse events (AEs) and serious AEs (SAEs) within 21 days of vaccination. One hundred and ninety participants were enrolled to each vaccine group. QIV induced GMTs to each A and B strain that were noninferior to those induced by the 2009–2010 and 2008–2009 TIVs (i.e., lower limit of the two-sided 95% confidence interval of the ratio of GMTQIV/GMTTIV>0.66 for each strain). Rates of seroprotection and seroconversion were similar in all groups. Incidence and severity of solicited injection-site and systemic reactions, AEs, and SAEs were similar among groups. QIV, containing two B strains (one from each B lineage), was as safe and immunogenic as licensed TIV. QIV has the potential to be a useful alternative to TIV and offer protection against both B lineages.

•We studied the serum antibody response in patients receiving chemotherapy.•Overall antibody response to the influenza virus vaccine is adequate.•Breast cancer patients mount the best serum antibody response early after receiving chemotherapy (≤day 5). Higher rates of hospitalization and mortality are described in oncology patients with influenza virus infection compared to the general population. Yearly influenza vaccination is recommended for patients treated with chemotherapy. The optimal moment to administer the vaccine during a treatment cycle has not been studied extensively. During the influenza season 2011–2012 we conducted a multicenter randomized controlled trial (OFLUVAC, NTR2858, no sponsoring) in the Netherlands. Patients receiving adjuvant chemotherapy for breast or colorectal cancer were randomized between early (day 5 after chemotherapy) and late (day 16 after chemotherapy) vaccination with the influenza virus vaccine (Influvac® 2011/2012—Vaxigrip® 2011/2012). Influenza virus-specific antibody titres were determined before, 3 and 12 weeks after vaccination by haemagglutination inhibition. Thirty-eight breast cancer patients (early=21; late=17) and 18 colorectal cancer patients (early=8; late=10) were analyzed. In breast cancer patients overall serologic responses were adequate. A statistically significant higher response in patients who received early compared to late vaccination in the chemotherapy cycle was observed. Geometric mean titres post vaccination on day 5 versus day 16 were 69.3 versus 27.4 (H3N2), 76.4 versus 17.5 (H1N1) and 34.4 versus 26.0 (B/Brisbane), respectively. In colorectal cancer patients overall serologic responses were adequate, no significant difference was found between early and late vaccination. Geometric mean titres post vaccination on day 5 versus day 16 were 170.1 versus 192.4 (H3N2), 233.0 versus 280.8 (H1N1) and 62.6 versus 75.9 (B/Brisbane), respectively. Overall antibody response to the influenza virus vaccine in patients treated with chemotherapy for breast or colorectal cancer patients is adequate. Breast cancer patients seem to mount the best antibody response when vaccinated early after a chemotherapy cycle (≤day 5). No difference was found between early and late vaccination in colorectal cancer patients.

Background: Autologous serum therapy aims to supplement the existing pharmacotherapy in chronic urticaria by decreasing the antihistamine pill-burden and maintaining symptom-free interval. Subcutaneous autologous serum therapy further modifies the amount of serum (2 mL to 1 mL) and gauge of a needle (24G to 31G) to improve compliance and facilitate ease of application. Objectives: To assess clinical effectiveness and safety of subcutaneous autologous serum therapy versus conventional intramuscular autologous serum therapy and to compare the quality of life in the two treatment arms. Methods: Institution-based, assessor-blind, prospective, randomized, parallel-group, active-controlled trial with 32 patients in each treatment arm and analyzed on a modified intention to treat principle. After baseline autologous serum skin test, autologous serum was injected as per randomization every week for 9 consecutive weeks. Results: Among the study population, conventional intramuscular autologous serum therapy and subcutaneous autologous serum therapy had a comparable duration of disease (P = 0.164, Mann-Whitney U test), autoreactive status (P = 0.796), urticaria total severity score (P = 0.637) and urticaria activity score summed up over 7 days (P = 0.982). Both urticaria activity score summed up over 7 days and total severity score along with antihistamine pill-burden reduced significantly (P < 0.001, Friedman's analysis of variance) in both subcutaneous autologous serum therapy and conventional intramuscular autologous serum therapy from first follow-up onwards (P < 0.05, Post hoc Dunn's test). Significant improvement was noted in patient's as well as physician's global assessment of disease activity improvement scale (P < 0.001, Friedman's analysis of variance). Intergroup analysis showed that there was no significant difference in urticaria activity score summed up over 7 days either at baseline (P = 0.982, Mann-Whitney U test) or at study end (P = 0.398, Mann-Whitney U test). Similar comparable results were found in the total severity score at the end of the study (P = 0.345, Mann-Whitney U test). Dermatology life quality index showed marked improvement with both types of treatment (P < 0.0001, Wilcoxon test), and the intergroup comparison showed comparable dermatology life quality index values (P = 0.994, Mann-Whitney U test). The pain score at the injection site was more with conventional intramuscular autologous serum therapy than subcutaneous autologous serum therapy (P = 0.0115, Mann-Whitney test). Younger age and lower baseline total severity scores were associated with a better therapeutic response. Baseline urticaria activity score added up over a period of 7 days and total severity scores and the diameter of lesions showed a positive correlation with response pattern. Limitation: Basophil histamine release assay not done. Logistics could not support follow-up beyond the end of treatment. Conclusion: Subcutaneous autologous serum therapy is not inferior to conventional intramuscular autologous serum therapy with the additional advantage of less pain and operational feasibility.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a respiratory disease called coronavirus disease 2019 (COVID-19), the spread of which has led to a pandemic. An effective preventive vaccine against this virus is urgently needed. As an essential step during infection, SARS-CoV-2 uses the receptor-binding domain (RBD) of the spike protein to engage with the receptor angiotensin-converting enzyme 2 (ACE2) on host cells 1 , 2 . Here we show that a recombinant vaccine that comprises residues 319–545 of the RBD of the spike protein induces a potent functional antibody response in immunized mice, rabbits and non-human primates ( Macaca mulatta ) as early as 7 or 14 days after the injection of a single vaccine dose. The sera from the immunized animals blocked the binding of the RBD to ACE2, which is expressed on the cell surface, and neutralized infection with a SARS-CoV-2 pseudovirus and live SARS-CoV-2 in vitro. Notably, vaccination also provided protection in non-human primates to an in vivo challenge with SARS-CoV-2. We found increased levels of RBD-specific antibodies in the sera of patients with COVID-19. We show that several immune pathways and CD4 T lymphocytes are involved in the induction of the vaccine antibody response. Our findings highlight the importance of the RBD domain in the design of SARS-CoV-2 vaccines and provide a rationale for the development of a protective vaccine through the induction of antibodies against the RBD domain. A recombinant vaccine that targets the receptor-binding domain of the spike protein of SARS-CoV-2 induces a potent antibody response in immunized mice, rabbits and non-human primates, and protects primates from infection with the virus.

Background: Patients with chronic urticaria (CU) frequently exhibit positive skin test reactions to autologous serum (ASST). Therapies aimed at inducing tolerance to circulating histamine-releasing factors in ASST+ CU patients, e.g. by treatment with autologous whole blood (AWB), have not yet been tested. Objective: To test whether ASST+ CU patients can benefit from repeated low-dose intramuscular injections of AWB. Methods: We characterized CU severity and duration, anti-Fc Ε RI and anti-IgE expression, use of antihistamines, and quality of life in 56 CU patients (ASST+: 35, ASST–: 21) and assessed the therapeutic effects of 8 weekly AWB injections in a randomized, placebo-controlled, single-blind, parallel-group trial. Results: Numbers, size, intensity, and/or duration of CU symptoms, quality of life, as well as expression of anti-Fc Ε RI or anti-IgE were similar in ASST+ and ASST– CU patients. However, CU in ASST+ patients was of longer duration and required markedly more antihistaminic medication. Interestingly, ASST+ patients, but not ASST– patients, showed significantly (1) reduced CU activity, (2) decreased use of antihistamines, and (3) improved quality of life after AWB treatment. Placebo treatment was ineffective in both groups, but differences of AWB and placebo treatment responses did not achieve statistical significance in either group, most likely due to the limited number of patients treated. Conclusion: Our findings suggest that ASST+ CU is clinically different from other CU subforms and that ASST+ CU patients can benefit from AWB therapy.

Current SARS-CoV-2 vaccines are losing efficacy against emerging variants and may not protect against future novel coronavirus outbreaks, emphasizing the need for more broadly protective vaccines. To inform the development of a pan-coronavirus vaccine, we investigated the presence and specificity of cross-reactive antibodies against the spike (S) proteins of human coronaviruses (hCoV) after SARS-CoV-2 infection and vaccination. We found an 11- to 123-fold increase in antibodies binding to SARS-CoV and MERS-CoV as well as a 2- to 4-fold difference in antibodies binding to seasonal hCoVs in COVID-19 convalescent sera compared to pre-pandemic healthy donors, with the S2 subdomain of the S protein being the main target for cross-reactivity. In addition, we detected cross-reactive antibodies to all hCoV S proteins after SARS-CoV-2 vaccination in macaques and humans, with higher responses for hCoV more closely related to SARS-CoV-2. These findings support the feasibility of and provide guidance for development of a pan-coronavirus vaccine.

The influenza virus neuraminidase (NA) is a promising target for next-generation influenza vaccines but standardised protocols for NA-based serological assays are lacking. Previous studies have demonstrated discordant results from haemagglutination inhibition and live virus microneutralization assays when comparing matched serum and plasma samples. It is therefore important to consider the choice of serum or plasma samples in assays measuring influenza virus NA-specific antibodies. Here, we compared antibody titres against influenza A and B virus NAs in matched serum and different types of plasma using an enzyme-linked lectin assay (ELLA) and an enzyme-linked immunosorbent assay (ELISA). We observed good correlations between titres determined in serum and different types of plasma. However, there was variable and often poor agreement in the nominal titre values obtained from serum and different kinds of plasma in both ELLA and ELISA, with plasma samples often resulting in lower titres compared to serum samples. We also found differences in NA-specific responses to seasonal influenza vaccination assessed in serum versus plasma. Overall, our data suggest discrepancies between NA-specific antibody measurements in serum and plasma. Therefore, the consistent use of serum should be considered in standardising NA-based serological assays.

Understanding antibody responses to SARS-CoV-2 is indispensable for the development of containment measures to overcome the current COVID-19 pandemic. Recent studies showed that serum from convalescent patients can display variable neutralization capacities. Still, it remains unclear whether there are specific signatures that can be used to predict neutralization. Here, we performed a detailed analysis of sera from a cohort of 101 recovered healthcare workers and we addressed their SARS-CoV-2 antibody response by ELISA against SARS-CoV-2 Spike receptor binding domain and nucleoprotein. Both ELISA methods detected sustained levels of serum IgG against both antigens. Yet, the majority of individuals from our cohort generated antibodies with low neutralization capacity and only 6% showed high neutralizing titers against both authentic SARS-CoV-2 virus and the Spike pseudotyped virus. Interestingly, higher neutralizing sera correlate with detection of -IgG, IgM and IgA antibodies against both antigens, while individuals with positive IgG alone showed poor neutralization response. These results suggest that having a broader repertoire of antibodies may contribute to more potent SARS-CoV-2 neutralization. Altogether, our work provides a cross sectional snapshot of the SARS-CoV-2 neutralizing antibody response in recovered healthcare workers and provides preliminary evidence that possessing multiple antibody isotypes can play an important role in predicting SARS-CoV-2 neutralization.