ABSTRACT
We developed surveillance guidance for COVID-19 in 9 temporary camps for displaced persons along the Thailand-Myanmar border. Arrangements were made for testing of persons presenting with acute respiratory infection, influenza-like illness, or who met the Thailand national COVID-19 Person Under Investigation case definition. In addition, testing was performed for persons who had traveled outside of the camps in outbreak-affected areas or who departed Thailand as resettling refugees. During the first 18 months of surveillance, May 2020-October 2021, a total of 6,190 specimens were tested, and 15 outbreaks (i.e., >1 confirmed COVID-19 cases) were detected in 7 camps. Of those, 5 outbreaks were limited to a single case. Outbreaks during the Delta variant surge were particularly challenging to control. Adapting and implementing COVID-19 surveillance measures in the camp setting were successful in detecting COVID-19 outbreaks and preventing widespread disease during the initial phase of the pandemic in Thailand.
Subject(s)
COVID-19 , Refugees , Respiratory Tract Diseases , Humans , COVID-19/epidemiology , SARS-CoV-2 , PandemicsABSTRACT
Despite the remarkable efficacy of COVID-19 vaccines, waning immunity, and the emergence of SARS-CoV-2 variants such as Omicron represents a major global health challenge. Here we present data from a study in non-human primates demonstrating durable protection against the Omicron BA.1 variant induced by a subunit SARS-CoV-2 vaccine, consisting of RBD (receptor binding domain) on the I53-50 nanoparticle, adjuvanted with AS03, currently in Phase 3 clinical trial (NCT05007951). Vaccination induced robust neutralizing antibody (nAb) titers that were maintained at high levels for at least one year after two doses (Pseudovirus nAb GMT: 2207, Live-virus nAb GMT: 1964) against the ancestral strain, but not against Omicron. However, a booster dose at 6-12 months with RBD-Wu or RBD-{beta} (RBD from the Beta variant) displayed on I53-50 elicited equivalent and remarkably high neutralizing titers against the ancestral as well as the Omicron variant. Furthermore, there were substantial and persistent memory T and B cell responses reactive to Beta and Omicron variants. Importantly, vaccination resulted in protection against Omicron infection in the lung (no detectable virus in any animal) and profound suppression of viral burden in the nares (median peak viral load of 7567 as opposed to 1.3x107 copies in unvaccinated animals) at 6 weeks post final booster. Even at 6 months post vaccination, there was significant protection in the lung (with 7 out of 11 animals showing no viral load, 3 out of 11 animals showing ~20-fold lower viral load than unvaccinated controls) and rapid control of virus in the nares. These results highlight the durable cross-protective immunity elicited by the AS03-adjuvanted RBD-I53-50 nanoparticle vaccine platform.
ABSTRACT
Although antivirals are important tools to control the SARS-CoV-2 infection, effective vaccines are essential to control the current pandemic. Plant-derived virus-like particle (VLP) vaccine candidates have previously demonstrated immunogenicity and efficacy against influenza. Here we report the immunogenicity and protection induced in macaques by intramuscular injections of VLP bearing SARS-CoV-2 spike protein (CoVLP) vaccine candidate formulated with or without Adjuvant System 03 (AS03) or cytosine phosphoguanine (CpG) 1018. Although a single dose of unadjuvanted CoVLP vaccine candidate stimulated humoral and cell-mediated immune responses, booster immunization (at 28 days after prime) and adjuvants significantly improved both responses with a higher immunogenicity and protection provided by AS03 adjuvanted CoVLP. Fifteen microgram CoVLP adjuvanted with AS03 induced a balanced IL-2 driven response along with IL-4 expression in CD4 T cells and mobilization of CD4 follicular helper cells (Tfh). Animals were challenged by multiple routes (i.e. intratracheal, intranasal and ocular) with a total viral dose of 106 plaque forming units of SARS-CoV-2. Lower viral replication in nasal swabs and broncho-alveolar lavage (BAL) as well as fewer SARS-CoV-2 infected cells and immune cell infiltrates in the lungs concomitant with reduced levels of pro-inflammatory cytokines and chemotactic factors in BAL were observed in the animals immunized with CoVLP adjuvanted with AS03. No clinical, pathologic or virologic evidences of vaccine associated enhanced disease (VAED) were observed in vaccinated animals. CoVLP adjuvanted with AS03 was therefore selected for vaccine development and clinical trials.
ABSTRACT
The development of a portfolio of SARS-CoV-2 vaccines to vaccinate the global population remains an urgent public health imperative. Here, we demonstrate the capacity of a subunit vaccine under clinical development, comprising the SARS-CoV-2 Spike protein receptor binding domain displayed on a two-component protein nanoparticle (RBD-NP), to stimulate robust and durable neutralizing antibody (nAb) responses and protection against SARS-CoV-2 in non-human primates. We evaluated five different adjuvants combined with RBD-NP including Essai O/W 1849101, a squalene-in-water emulsion; AS03, an alpha-tocopherol-containing squalene-based oil-in-water emulsion used in pandemic influenza vaccines; AS37, a TLR-7 agonist adsorbed to Alum; CpG 1018-Alum (CpG-Alum), a TLR-9 agonist formulated in Alum; or Alum, the most widely used adjuvant. All five adjuvants induced substantial nAb and CD4 T cell responses after two consecutive immunizations. Durable nAb responses were evaluated for RBD-NP/AS03 immunization and the live-virus nAb response was durably maintained up to 154 days post-vaccination. AS03, CpG-Alum, AS37 and Alum groups conferred significant protection against SARS-CoV-2 infection in the pharynges, nares and in the bronchoalveolar lavage. The nAb titers were highly correlated with protection against infection. Furthermore, RBD-NP when used in conjunction with AS03 was as potent as the prefusion stabilized Spike immunogen, HexaPro. Taken together, these data highlight the efficacy of the RBD-NP formulated with clinically relevant adjuvants in promoting robust immunity against SARS-CoV-2 in non-human primates.
