Viral infections at the animal-human interface-Learning lessons from the SARS-CoV-2 pandemic.

This Lilliput explores the current epidemiological and virological arguments for a zoonotic origin of the COVID-19 pandemic. While the role of bats, pangolins and racoon dogs as viral reservoirs has not yet been proven, a spill-over of a coronavirus infection from animals into humans at the Huanan food market in Wuhan has a much greater plausibility than alternative hypotheses such as a laboratory virus escape, deliberate genetic engineering or introduction by cold chain food products. This Lilliput highlights the dynamic nature of the animal-human interface for viral cross-infections from humans into feral white tail deer or farmed minks (reverse zoonosis). Surveillance of viral infections at the animal-human interface is an urgent task since live animal markets are not the only risks for future viral spill-overs. Climate change will induce animal migration which leads to viral exchanges between animal species that have not met in the past. Environmental change and deforestation will also increase contact between animals and humans. Developing an early warning system for emerging viral infections becomes thus a societal necessity not only for human but also for animal and environmental health (One Health concept). Microbiologists have developed tools ranging from virome analysis in key suspects such as viral reservoirs (bats, wild game animals, bushmeat) and in humans exposed to wild animals, to wastewater analysis to detect known and unknown viruses circulating in the human population and sentinel studies in animal-exposed patients with fever. Criteria need to be developed to assess the virulence and transmissibility of zoonotic viruses. An early virus warning system is costly and will need political lobbying. The accelerating number of viral infections with pandemic potential over the last decades should provide the public pressure to extend pandemic preparedness for the inclusion of early viral alert systems.

Do we need nasal vaccines against COVID 19 to suppress the transmission of infections?

Covid-19 vaccines have within the first year prevented about 14 million deaths but did not induce a strong mucosal immune response. Data from US, UK, Singapore and Israel showed a variable and mostly modest effects of vaccination on virus excretion during breakthrough infections. Contact studies showed decreased transmission of infection from vaccinated index cases, but the effect varied according to dominant virus type, with study type and the nature of the contact group and diminished with time after vaccination. Some researchers suspect that it is unlikely to stop the pandemic with injected vaccines alone. Promising animal experiments were conducted with mucosal vaccines. Mice nasally immunized with a chimpanzee adenovirus vector mounted a mucosal immune response, were protected against viral challenge after a single vaccine dose and suppressed nasal replication of the challenge virus. Phage T4 expressing SARS-CoV-2 spike and nucleocapsid induced a sterilizing lung immunity in nasally vaccinated mice. Also hamsters intranasally immunized with the prefusion-stabilized spike protein showed no infectious virus in nasal turbinates upon challenge. Other studies showed that intranasal vaccination with an adenovirus vaccine reduced but did not eliminated viral transmission from infected to naïve hamsters. Intranasal vaccination of rhesus macaques with adenovirus vaccines also substantially reduced or even suppressed viral replication in the upper and lower respiratory tract. Human data on mucosal SARS-CoV-2 vaccines are so far limited to safety and immunogenicity studies. Aerosolized adenovirus vaccines given either as a booster or as primary immunization were safe and induced similar or superior immune response than injected vaccines while an aerosolized influenza vectored vaccine induced only a weak humoral and cellular immune response. Overall 100 mucosal SARS-CoV-2 vaccines are in development and 20 are in clinical trials. First human trials demonstrate that this will not be an easy task.

On opinion, freedom of speech and its responsibilities.

Plato and Aristotle place opinion intermediate between knowledge and ignorance with all opinions under the suspicion of error. Kant summarized that opinion is a consciously insufficient judgement, subjectively and objectively. Belief is subjectively sufficient, but is recognized as being objectively insufficient. Only knowledge is subjectively and objectively sufficient. Despite this philosophically doubtful value of opinions, thinkers such as Milton, Locke, Montesquieu and Mill maintain that the freedom of opinion and speech are the basis of open societies but find limits when it represents a definite risk of damage, either to an individual or to the public. Also the UN Covenant on Civil and Political Rights proclaims the right to hold opinions without interference provided that it respects the rights or reputations of others and does not interfere with the protection of public health. Hate speech and propaganda for war are expressively prohibited. Postwar US politicians formulated the position that every man has a right to his own opinion, but no man has a right to be wrong in his facts. The impact of this discussion on opinions about control measures of the COVID-19 pandemic is explored in this editorial.

COVID-19: Omicron - the latest, the least virulent, but probably not the last variant of concern of SARS-CoV-2.

The Omicron variant rapidly became the dominant SARS-CoV-2 strain in South Africa and elsewhere. This review explores whether this rise was due to an increased transmission of the variant or its escape from population immunity by an extensively mutated spike protein. The mutations affected the structure of the spike protein leading to the loss of neutralization by most, but not all, therapeutic monoclonal antibodies. Omicron also shows substantial immune escape from serum antibodies in convalescent patients and vaccinees. A booster immunization increased, however, the titre and breadth of antiviral antibody response. The cellular immune response against Omicron was largely preserved explaining a satisfying protection of boosted vaccinees against severe infections. Clinicians observed less severe infection with Omicron, but other scientists warned that this must not necessarily reflect less intrinsic virulence. However, in animal experiments with mice and hamsters, Omicron infections also displayed a lesser virulence than previous VOCs and lung functions were less compromised. Cell biologists demonstrated that Omicron differs from Delta by preferring the endocytic pathway for cell entry over fusion with the plasma membrane which might explain Omicron's distinct replication along the respiratory tract compared with Delta. Omicron represents a distinct evolutionary lineage that deviated from the mainstream of evolving SARS-CoV-2 already in mid-2020 raising questions about where it circulated before getting widespread in December 2021. The role of Omicron for the future trajectory of the COVID-19 pandemic is discussed.

The beginning and ending of a respiratory viral pandemic-lessons from the Spanish flu.

The COVID-19 pandemic goes into its third year and the world population is longing for an end to the pandemic. Computer simulations of the future development of the pandemic have wide error margins and predictions on the evolution of new viral variants of SARS-CoV-2 are uncertain. It is thus tempting to look into the development of historical viral respiratory pandemics for insight into the dynamic of pandemics. The Spanish flu pandemic of 1918 caused by the influenza virus H1N1 can here serve as a potential model case. Epidemiological observations on the shift of influenza mortality from very young and old subjects to high mortality in young adults delimitate the pandemic phase of the Spanish flu from 1918 to 1920. The identification and sequencing of the Spanish flu agent allowed following the H1N1 influenza virus after the acute pandemic phase. During the 1920s H1N1 influenza virus epidemics with substantial mortality were still observed. As late as 1951, H1N1 strains of high virulence evolved but remained geographically limited. Until 1957, the H1N1 virus evolved by accumulation of mutations ('antigenic drift') and some intratypic reassortment. H1N1 viruses were then replaced by the pandemic H2N2 influenza virus from 1957, which was in 1968 replaced by the pandemic H3N2 influenza virus; both viruses were descendants from the Spanish flu agent but showed the exchange of entire gene segments ('antigenic shift'). In 1977, H1N1 reappeared from an unknown source but caused only mild disease. However, H1N1 achieved again circulation in the human population and is now together with the H3N2 influenza virus an agent of seasonal influenza winter epidemics.

COVID-19 and children: medical impact and collateral damage.

Children mostly experience mild SARS-CoV-2 infections, but the extent of paediatric COVID-19 disease differs between geographical regions and the distinct pandemic waves. Not all infections in children are mild, some children even show a strong inflammatory reaction resulting in a multisystem inflammatory syndrome. The assessments of paediatric vaccination depend on the efficacy of protection conferred by vaccination, the risk of adverse reactions and whether children contribute to herd immunity against COVID-19. Children were also the target of consequential public health actions such as school closure which caused substantial harm to children (educational deficits, sociopsychological problems) and working parents. It is, therefore, important to understand the transmission dynamics of SARS-CoV-2 infections by children to assess the efficacy of school closures and paediatric vaccination. The societal restrictions to contain the COVID-19 pandemic had additional negative effects on children's health, such as missed routine vaccinations, nutritional deprivation and lesser mother-child medical care in developing countries causing increased child mortality as a collateral damage. In this complex epidemiological context, it is important to have an evidence-based approach to public health approaches. The present review summaries pertinent published data on the role of children in the pandemic, whether they are drivers or followers of the infection chains and whether they are (after elderlies) major sufferers or mere bystanders of the COVID-19 pandemic.

Can a combination of vaccination and face mask wearing contain the COVID-19 pandemic?

The COVID-19 pandemic is going into its third year with Europe again being the focus of major epidemic activity. The present review tries to answer the question whether one can come to grip with the pandemic by a combination of vaccinations and non-pharmaceutical interventions (NPIs). Several COVID-19 vaccines are of remarkable efficacy and achieve high protection rates against symptomatic disease, especially severe disease, but mathematical models suggest that the current vaccination coverage in many countries is insufficient to achieve pandemic control. NPIs are needed as complementary measures because recent research has also revealed the limits of vaccination alone. Here, we review the evidence for efficacy of face mask wearing in various settings. Overall pooled analysis showed significant reduction in COVID-19 incidence with mask wearing, although heterogeneity between studies was substantial. Controlled trials of mask wearing are difficult to conduct, separating mask wearing effects in population studies from the impact of other NPIs is challenging and the efficacy of masks depend on mask material and mask fit. The combination of vaccination and mask wearing is potentially synergistic since vaccination protects so far well from disease development (the omicron variant is currently an unknown) but immunity from infection wanes over few months after vaccination. In comparison, masks interfere with the virus transmission process at a level of a physical barrier independent of coronavirus variant. Vaccination and masks are much less costly to apply than other NPI measures which are associated with high economic and social costs, but paradoxically both measures are the target of a vocal opposition by a sizable minority of the society. In parallel with biomedical research, we need more social science research into this opposition to guide political decisions on how to end the pandemic.

mRNA vaccines against COVID-19: a showcase for the importance of microbial biotechnology.

Pfizer-BioNTech and Moderna developed in record time mRNA vaccines against COVID-19 of high efficacy. The modest protection achieved with a similarly designed mRNA from CureVac underlines the importance of biotechnological details in formulation such as replacement of uridine by pseudouridine in the mRNA encoding the SARS-CoV-2 spike protein or the lipid composition of the nanoparticle coating the mRNA. Phase 3 vaccine trials and vaccine studies in special subject groups as well observational studies in whole populations confirmed the real-world vaccine efficacy against symptomatic disease, particularly against severe COVID-19 cases and to a lesser extent against mild SARS-CoV-2 infections. mRNA vaccine protection extended also to the alpha and beta variant viruses. The surge of delta variants led to an increase of infections and cases even in populations which achieved high vaccine coverage. This efficacy decline resulted to a lesser extent from a weaker neutralization of the delta variant but mostly from a waning vaccine protection over time. Data from Israel documented the efficacy of a third 'booster' injection 5 months after the second injection in older segments of the population. Adverse reactions consisted of transient injection site pain, headache, muscle pain, fatigue, fever and chills. Extensive surveillance studies documented a good safety profile revealing only a non-significant increase in transient facial nerve paralysis and a significant, but modest increase in myocarditis in vaccinated young males that was lower than the myocarditis risk induced by SARS-CoV-2 infection.

Host-modifying drugs against COVID-19: some successes, but not yet the breakthrough.

After reviewing antiviral drugs (Brüssow Environmental Microbiology 2021) the present review summarizes the results of clinical trials with host-modifying drugs in COVID-19 patients. Clinical benefits were observed with different immunomodulators. The variable outcomes of trials with the interleukin 6 receptor inhibitor tocilizumab demonstrated that treatment benefits might only be present in specific subgroups of patients or in specific infection stages. A meta-analysis of trials with the interleukin 1 receptor antagonist anakinra showed a survival benefit only in patients with hyperinflammation. The Janus kinase inhibitor baricitinib is an anti-inflammatory treatment that showed a clinical benefit in hospitalized patients who do not yet need supplementary oxygen. In contrast, the corticosteroid dexamethasone showed mortality reducing effects that were limited to patients on ventilation or in need of supplementary oxygen. Therapeutic dose of anticoagulation met the criteria for inferiority in severe cases, but showed a small survival benefit in non-severe COVID-19 patients. Large trials with colchicine showed a small or no survival benefit. Azithromycin, an antibiotic with immunomodulatory activity, showed no effects in numerous clinical trials. The trials showed a clear need for new drugs instead of repurposed drugs and drugs that specifically target the SARS-CoV-2 virus or the pathology developing in COVID-19 patients.

Clinical trials with antiviral drugs against COVID-19: some progress and many shattered hopes.

Vaccines and drugs are the cornerstones in the fight against the SARS-CoV-2 pandemic. While vaccines were a success story, the development of antiviral drugs against SARS-CoV-2 turned out to be difficult. For an accelerated use of antivirals in the clinic, most SARS-CoV-2 antivirals represented repurposed drugs. The present article summarizes the outcomes of clinical trials with antiviral drugs in COVID-19 patients. Many antiviral drugs failed to demonstrate beneficial effects or showed mixed results. One reason for the low success rate of clinical trials was shortcomings of antiviral tests in cell culture systems and another reason was the abundance of ill-coordinated and underpowered clinical trials. However, large pragmatic clinical trials particularly of the British RECOVERY trial series demonstrated that even under emergency situation drug trials can be conducted in a timely way such that the therapy of COVID-19 patients can be based on evidence basis instead on expert opinion or even worse on political pressure.

What we can learn from the dynamics of the 1889 'Russian flu' pandemic for the future trajectory of COVID-19.

A study of the contemporary medical literature for patient symptoms from the so-called 'Russian flu' pandemic from 1889 revealed clinical observations that resemble COVID-19 (Brüssow and Brüssow, 2021, Microb Biotechnol). If one accepts the hypothesis that this pandemic was a prior coronavirus epidemic, the dynamics of the 'Russian flu' from 1889 might give us some ideas about the future trajectory of the COVID-19 pandemic. The present report compiles and reviews the contemporary data published on the temporal and geographical spread of the 'Russian flu', its epidemic wave structure and possible later resurgence. The historical record of past pandemics might thus provide us not with predictions, but 'retrodictions' on possible future scenarios for the COVID-19 pandemic.

COVID-19: From pathogenesis models to the first drug trials.

The number of people infected with SARS-CoV-2, and sadly dying from COVID-19, has exploded, and so the amount of literature on the novel coronavirus and the disease it causes has increased proportionately. The case numbers in some countries are beyond the epidemic peak, but the uncertainty about a second wave keeps politicians and societies under pressure. Appropriate decision-making and winning support from the population depends on precise scientific information rather than leaving the field to scaremongers of all proveniences. This mini-review is an update of earlier reports (Brüssow, Microb Biotechnol 2020a;13:607; Brüssow, Microb Biotechnol 2020b; https://doi.org/10.1111/1751-7915.13592).

COVID 19: challenges for virologists in the food industry.

The COVID-19 pandemic is not only a challenge for public health and hospitals, but affects many aspects of our societies. This Lilliput minireview deals with problems that the pandemic causes for the food industry, addressing the presence and persistence of SARS-CoV-2 in the food environment, methods of virus inactivation and the protection of the food worker and the consumer. So far food has not been implicated in the transmission of the infection, but social disruptions caused by the pandemic could cause problems with food security.

Immunology of COVID-19.

The immune response to SARS-CoV-2 reveals a delicate balance between protective effects and harmful pathological reactions and can possibly explain the highly variable disease manifestations in subjects infected with this novel coronavirus. A better understanding of the anti-viral immune response is not only critical for vaccine development but might also provide targets for pharmaceutical and immunological treatment options. Recent research literature on immune aspects of COVID-19 is summarized in this review with an outlook how bats have evolved to live with these viral infections.

The Novel Coronavirus - A Snapshot of Current Knowledge.

Another animal to human transmission of a coronavirus occurred in December 2019 on a live animal market in the Chinese city of Wuhan causing an epidemic in China, reaching now different continents. This minireview summarizes the research literature on the virological, clinical and epidemiological aspects of this epidemic published until end of February 2020.

COVID-19: test, trace and isolate-new epidemiological data.

In the absence of an efficient drug treatment or a vaccine, the control of the COVID-19 pandemic relies on classic infection control measures. Since these means are socially disruptive and come with substantial economic loss for societies, a better knowledge of the epidemiology of the new coronavirus epidemic is crucial to achieve control at a sustainable cost and within tolerable restrictions of civil rights.

Clinical evidence that the pandemic from 1889 to 1891 commonly called the Russian flu might have been an earlier coronavirus pandemic.

Contemporary medical reports from Britain and Germany on patients suffering from a pandemic infection between 1889 and 1891, which was historically referred to as the Russian flu, share a number of characteristics with COVID-19. Most notable are aspects of multisystem affections comprising respiratory, gastrointestinal and neurological symptoms including loss of taste and smell perception; a protracted recovery resembling long covid and pathology observations of thrombosis in multiple organs, inflammation and rheumatic affections. As in COVID-19 and unlike in influenza, mortality was seen in elderly subjects while children were only weakly affected. Contemporary reports noted trans-species infection between pet animals or horses and humans, which would concur with a cross-infection by a broad host range bovine coronavirus dated by molecular clock arguments to an about 1890 cross-species infection event.

COVID-19: long covid and its societal consequences.

COVID-19 is an acute, highly transmissible respiratory infection that is potentially lethal, but often mild, sometimes asymptomatic, especially in the young. However, it has become clear that, in some patients, there may be sequelae involving tissues other than the lung, resulting in other types of morbidity, and sometimes longer term consequences that are often termed 'long covid'. In this Lilliput, we summarize recent findings about COVID-19 sequelae, with a particular focus on long covid. We also discuss some of the long scars that COVID-19 and long covid will collectively leave on society that we term Societal Long Covid.

COVID-19: vaccine's progress.

Under the pressure of the COVID-19 pandemic, vaccines were developed and rolled out into mass vaccination campaigns at incredible speed. What normally takes a decade was worked out within a year. Vaccines were produced along many different platforms ranging from inactivated whole virus vaccines over adenovirus-vectored vaccines, recombinant protein vaccines and nanoparticles to mRNA vaccines. Several vaccines went through preclinical testing and completed successful phase 1 to phase 3 clinical trials. The first evaluations of national vaccination campaigns document astonishing high levels of protection against disease. The present article summarizes the published reports leading to these striking achievements with vaccines based on different concepts.

COVID-19: emergence and mutational diversification of SARS-CoV-2.

The origin of the SARS-CoV-2 virus is not yet defined, but a viral zoonosis from bats - with or without an alternative animal as an intermediate host - is still the most likely hypothesis. The intensive virological and epidemiological research combined with massive sequencing efforts of whole viral genomes allowed an unprecedented analysis of an unfolding pandemic at the level of viral evolution with the documentation of extinction events, prevalence increases and rise to dominance for different viral lineages that provide not only fundamental insights into mechanisms of viral evolution, but influence also public health measures to contain the virus.