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Population Dynamics of Pathogens
Published in Leonhard Held, Niel Hens, Philip O’Neill, Jacco Wallinga, Handbook of Infectious Disease Data Analysis, 2019
The previous sections focus largely on pathogens whose local chains-of-transmission remains unbroken. However, a number of particularly acute, immunizing infections persist in “consumer-resource metapopulation” where the infection depletes the susceptible pool so deeply that frequent extinctions occur. Persistence is only secured through spatial coupling among asynchronous locally non-persistent chains-of-transmission. In disease ecology, a metapopulation is the setting where the host population is subdivided into many connected sub-populations (e.g., multiple cities). Influenza in non-tropical areas typify this behavior. Mass-vaccination has pushed the persistence of many childhood diseases such as mumps and measles from local to metapopulation. The spatial dynamics of infectious disease is therefore of great basic and applied importance.
Priority setting, rationing and the consumer role
Published in Penelope Mullen, Peter Spurgeon, Priority Setting and The Public, 2018
Penelope Mullen, Peter Spurgeon
Attempts to explain the ‘rule of rescue’ or the ‘statistical lives paradox’ are often couched in terms of the greater emotional attachment to an identified individual rather than to as yet unidentified individuals, or sympathy for the individual in greater need as against a larger number in lesser need. Perhaps, however, certainty and risk play a part. Although not without controversy, mass vaccination can be advocated even where a small number of individuals will be severely damaged by the vaccine. The very low risk of severe injury is considered to be outweighed by the much higher risk of the disease against which the vaccination is given, resulting in a net health gain. But let us change the scenario slightly, if somewhat implausibly. Let us assume that it is known in advance which specific individuals are going to suffer severe damage but also that the only method of administering that vaccine requires that everyone is vaccinated, i.e. it is impossible to exclude any individual. All other factors (i.e. the severity of damage and number affected, the risk and severity of the disease being vaccinated against) remain the same, so the same net health gain would be achieved as in the earlier scenario. Would that mass vaccination programme still be advocated? If not, would this be solely because those who were to suffer severe injury were identified in advance? Or would the decision be affected by the related, but not identical, fact that what, in the original scenario, was a very low risk of severe injury for everyone is now a 100% certainty for a few and a zero risk for the many?
Medical theory, medical care, and preventive medicine
Published in Lois N. Magner, Oliver J. Kim, A History of Medicine, 2017
A higher rate of adverse effects would be expected if mass vaccination became routine again because of the increased numbers of people with conditions that weaken the immune system: people with HIV/AIDS, organ transplant patients, people taking chemotherapy or steroid drugs, and people with autoimmune diseases. People who had been vaccinated would have to avoid transmitting vaccinia virus to vulnerable unvaccinated people, including pregnant women and babies less than a year old. Moreover, vaccinia virus can spread from the site of inoculation and cause infection of the skin, eyes, and brain. Some complications can be modified by injection of vaccine immune globulin (VIG), which is derived from the blood of people who have been vaccinated against smallpox. VIG was developed in the 1950s, but it was never subjected to rigorous clinical studies. VIG can be used to protect people who cannot be vaccinated, including pregnant women and people with compromised immune systems. Because so few vaccinations have been done since the 1970s, very little VIG would be available.
Seroprevalence of SARS-CoV-2 in Mexican Health Care Workers after Two Years of the Pandemic: The Picture of an Ophthalmic Medical Centre
Published in Ophthalmic Epidemiology, 2023
Yonathan Garfias, Fátima Sofía Magaña-Guerrero, Beatriz Buentello-Volante, Itayetzin Beurini Cruz Vega, Ilse Castro Salas, Paola de Jesús Sánchez Cisneros, José Eduardo Aguayo Flores, Angel Gustavo Salas Lais, José Esteban Muñoz Medina, Verónica Mata-Haro, Mónica Reséndiz-Sandoval, Verónica A Vázquez-García, Jesús Hernández
In the present study, we investigated the impact of the SARS-CoV-2 vaccination on seroprevalence in a cohort of HCWs at an ophthalmic medical center. All HCWs were successfully immunized, as in the other cohorts.13 We previously reported that 20% of HCWs in our ophthalmological center were seropositive for SARS-CoV-2 before vaccination because of the natural exposure to SARS-CoV-2.9 In the present study, 98.4% of patients were seropositive for SARS-CoV-2 after the national vaccination program. Thus, vaccination exerted a significant (p < .001) effect on seroconversion (increase of 78.4%). This result indicates that mass vaccination significantly induced an effective immune response.14 Overall, all vaccines significantly increased the serum anti-SARS-CoV-2 IgG antibody levels. AZD1222, BNT162b2, and Sputnik-V generated the highest serum antibody titers compared to the other vaccines (Ad-5nCOV, CoronaVac, mRNA-1273, and Ad26.COV2-S). We confirmed that there were differences in the induction of immunity between the vaccines. To associate the vaccination time with the quantity of serum IgG anti-S1/S2 antibodies, we determined that serum antibodies were independent of vaccination time for all vaccines (data not shown). These results suggest that serum antibodies are present for at least 200 days without any decay, which is in agreement with previous reports that memory immunity is present for at least six months after vaccination.15
COVID-19 pandemic: SARS-CoV-2 specific vaccines and challenges, protection via BCG trained immunity, and clinical trials
Published in Expert Review of Vaccines, 2021
Wenping Gong, Ashok Aspatwar, Shuyong Wang, Seppo Parkkila, Xueqiong Wu
Mass vaccination is a very effective public health intervention during the COVID-19 pandemic. However, after COVID-19 vaccines have become available, transporting these vaccines quickly and efficiently from manufacturers to hospitals or communities is the next crucial step in the whole process of vaccine circulation [92]. The most significant difference between the vaccine supply chain and transportation of other goods lies in the cold chain logistics requirements [93]. The transportation and storage of inactivated vaccines, such as the Sinovac vaccine and Sinopharm’s COVID-19 vaccine need to be carried out at 2°C to 8°C, with a complete industrial chain and mature technology [94]. However, Pfizer/BioNTech’s BNT162b2 and Moderna mRNA-1273 require temperatures of −80°C and −20°C, respectively. Thus, the delivery of these mRNA vaccines requires specialized freezers that most doctors’ offices and pharmacies are unlikely to have on-site. As such, the easiest solutions are aircraft transportation and dry ice storage. However, the global air cargo throughput is insufficient to distribute these COVID-19 vaccines internationally and the instability of dry ice may render the vaccine ineffective [95]. The WHO estimates a huge risk of losing COVID-19 vaccines due to cold chain failures and nonfunctional freezers [96]. Therefore, the best solution may be to use the ultra-low temperature freezer as the transport carrier but this equipment is expensive and difficult to obtain, so solving the challenges in the cold chain logistics of COVID-19 vaccines in a short time remains difficult.
Lessons from mass vaccination response to meningococcal B outbreaks at US universities
Published in Postgraduate Medicine, 2020
Justine Alderfer, Raul E. Isturiz, Amit Srivastava
Based on CDC guidance [54], mass vaccination campaigns have been an integral part of MenB outbreak control efforts at US college campuses [38]. Meningococcal outbreaks cause substantial disruptive anxiety within affected populations and impose an unanticipated financial burden on colleges to support containment tactics aimed at controlling the disease [4,5], which may include chemoprophylaxis of close contacts, expanded chemoprophylaxis, vaccination, and education and hygiene campaigns [54]. As described by the CDC, considerations in implementing mass vaccination include the size of the target population, the likelihood of ongoing transmission, feasibility of the campaign, and the timing of vaccination relative to case identification. For colleges, a meningococcal outbreak response is an urgent, massive, and distributed effort; beyond on-campus vaccination clinics, both licensed MenB vaccines have been administered at local pharmacies and by students’ own doctors [55].