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NDV-HXP-S is a recombinant Newcastle disease virus–based vaccine against SARS-CoV-2, which expresses an optimized (HexaPro) spike protein on its surface. The vaccine can be produced in embryonated chicken eggs using the same process as that used for the production of the vast majority of influenza virus vaccines. Here, we performed a secondary analysis of the antibody responses after vaccination with inactivated NDV-HXP-S in a phase 1 clinical study in Thailand. The SARS-CoV-2 neutralizing and spike protein binding activity of NDV-HXP-S postvaccination serum samples was compared to that of samples from mRNA BNT162b2 (Pfizer) vaccinees. Neutralizing activity of sera from NDV-HXP-S vaccinees was comparable to that of BNT162b2 vaccinees, whereas spike protein binding activity of the NDV-HXP-S vaccinee samples was lower than that of sera obtained from mRNA vaccinees. This led us to calculate ratios between binding and neutralizing antibody titers. Samples from NDV-HXP-S vaccinees had binding to neutralizing activity ratios that were lower than those of BNT162b2 sera, suggesting that NDV-HXP-S vaccination elicits a high proportion of neutralizing antibodies and low non-neutralizing antibody titers. Further analysis showed that, in contrast to mRNA vaccination, which induces strong antibody titers to the receptor binding domain (RBD), the N-terminal domain, and the S2 domain, NDV-HXP-S vaccination induced an RBD-focused antibody response with little reactivity to S2. This finding may explain the high proportion of neutralizing antibodies. In conclusion, vaccination with inactivated NDV-HXP-S induces a high proportion of neutralizing antibodies and absolute neutralizing antibody titers that are comparable to those elicited by mRNA vaccination. A New(castle disease virus) vaccine for SARS-CoV-2: SARS-CoV-2 vaccines have been essential in combating the ongoing COVID-19 pandemic, but room for improvement remains. Here, Carreño et al. analyzed immune responses in individuals vaccinated with a Newcastle disease virus-based SARS-CoV-2 vaccine, NDV-HXP-S. This vaccine can be produced in embryonated chicken eggs, similar to the majority of influenza vaccines, making it readily translatable. The authors found that vaccination with NDV-HXP-S elicited a higher proportion of neutralizing antibodies against SARS-CoV-2 than vaccination with the BNT162b2 mRNA vaccine. NDV-HXP-S vaccinees also had a response more focused on the receptor binding domain. Together, these data highlight the promise of NDV-HXP-S, which has moved into a Phase III trial in Thailand. —CM [ABSTRACT FROM AUTHOR]

The emergence and spread of highly pathogenic avian influenza (H5N1) viruses have raised global concerns of a possible human pandemic, spurring efforts towards H5N1 influenza vaccine development and improvements in vaccine administration methods. We previously showed that a prime-boost vaccination strategy induces robust and broadly cross-reactive antibody responses against the hemagglutinin globular head domain. Here, we specifically measure antibodies against the conserved hemagglutinin stem region in serum samples obtained from the prior study to determine whether stalk-reactive antibodies can also be induced by the prime-boost regimen. Serum samples collected from 60 participants before vaccination and on days 7, 28 and 90 following boosting vaccination were used in this study. 40 participants received two doses of live attenuated H5N2 vaccine (LAIV H5N2) followed by one dose of inactivated H5N1 vaccine a year later, while 20 participants received only the inactivated H5N1 vaccine. We tested these serum samples for stalk-reactive antibodies via enzyme-linked immunosorbent (ELISA) and microneutralization assays. Stalk-specific antibody levels measured by both assays were found to be significantly higher in primed individuals than the unprimed group. ELISA results showed that 22.5, 70.5 and 57.5% of primed participants had a four-fold or more increase in stalk antibody titers on days 7, 28 and 90 following boosting vaccination, respectively; whereas the unprimed group had no increase. Peak geometric mean titers (GMT) for stalk antibodies in the LAIV H5N2 experienced group (24,675 [95% CI; 19,531–31,174]) were significantly higher than those who received only the inactivated H5N1 vaccine (8877 [7140–11,035]; p < 0·0001). Moreover, stalk antibodies displaying neutralizing activity also increased in primed participants, but not in the unprimed group. Our finding emphasizes the importance of prime-boost vaccination for effectively inducing stalk antibodies, which is an attractive target for developing vaccines that induce stalk reactive antibodies. [ABSTRACT FROM AUTHOR]

Abstract: In 2005, a year after highly pathogenic avian influenza outbreaks in Thailand, the Thai Government issued a National Strategy Plan for Pandemic Influenza Preparedness, a major objective of which was the domestic production of seasonal influenza vaccine. It was considered that sustained influenza vaccine production was the best guarantee of a pandemic vaccine in the event of a future pandemic. The Government decided to provide funds to establish an industrial-scale influenza vaccine production plant, and gave responsibility for this challenging project to the Government Pharmaceutical Organization (GPO). In 2007, with support from the World Health Organization (WHO), the GPO started to develop egg-based, trivalent inactivated influenza vaccine (IIV) in a renovated pilot plant. In early 2009, during the second year of the project, the GPO turned its attention to develop a pandemic live attenuated influenza vaccine (PLAIV) against the influenza A (H1N1) virus. By December 2010, the H1N1 PLAIV had successfully completed Phase II clinical trials and was awaiting registration approval from the Thai Food and Drug Administration (TFDA). The GPO has also started to develop an H5N2 PLAIV, which is expected to enter clinical trials in January 2011. The next step in 2011 will be the development and clinical evaluation of seasonal LAIV. To meet the needs of the national seasonal influenza vaccination programme, the GPO aims to produce 2 million doses of trivalent IIV in 2012 and progressively increase production to the maximum annual capacity of 10 million doses. This article relates how influenza vaccine production capacity was developed and how major challenges are being met in an expeditious manner, with strong local and global commitment. [Copyright &y& Elsevier]