COVID-19 Evolving Evidence

Public health experts describe their experience of quarantine in China. They state ‘some countries strengthened the controls of inbound passengers—for example, increasing quarantine from 14 days to 21 or even 28 days. Such extended quarantine measures are probably an over-reaction to the risk’.

The story of Ivermectin is one of science, pseudoscience, politics and fraud. For anyone interested in the evidence, this is an excellent analysis.

Hong Kong's leading longevity is the result of fewer diseases of poverty while suppressing the diseases of affluence. A unique combination of economic prosperity and low levels of smoking with development contributed to this achievement. As such, it offers a framework that could be replicated through deliberate policies in developing and developed populations globally.

In this systematic review of 57 studies comprising more than 250,000 survivors of COVID-19 more than half had at least one long term sequelae after 6 months. Long Covid may be expected to place a significant burden on health systems in the future. We have collated a Long Covid Resource centre to pool information on this issue as the evidence evolves.

The CDC are now publishing evidence of age and vaccination status for both hospitalization and death. The data confirms the significant increase in risk associated with both age and lack of vaccination.

A recent study in Hong Kong explored attitudes to quarantine in people who had been quarantined within the city. This study highlights the need for inclusiveness, reasonableness, openness and transparency when making decisions regarding quarantine measures in order to mitigate negative psychosocial consequences.

The Covid pandemic has had an enormous impact on mental health, anxiety and depression. This study considers the evidence across 204 countries, and shows significant impact, especially among women and younger people.

In this study the vaccine efficacy against mild disease one month after vaccination was 88% by five months the efficacy had dropped to 47% which is consistent with studies showing a drop in antibody levels. However, the efficacy in preventing hospitalization remained high. 87% after 1 month and 88% after five months.

Science is about testing assumptions and challenging alternative hypotheses. Sometimes the evidence is blindingly obvious. Gardening, exercise, listening to music, hobbies and reading are associated with positive outcomes. Following the news on Covid, social media and TV are associated with negative outcomes.

Not only are natural antibody levels higher but they also elicit different pathway responses.

Denmark has vaccinated 97% of the population over 60 and relaxed all public health measures. Cases are slowly rising in the younger population but the majority are mild. The academic world is watching Denmark to see what endemic Covid looks like.

In this excellent study of a prison population in the USA there was a significant outbreak of Delta infection. 80% of the population was already vaccinated and for this reason the majority of infections were in vaccinated individuals. However, 3 out of the 4 hospitalizations and the only death were in unvaccinated prisoners. The lowest attack rates were in people who had been vaccinated but also had prior Covid. This supports findings from a recent Israeli study on the higher levels of immunity from vaccination plus natural infection.

This article in the Atlantic asks whether post-vaccination Covid is a different disease. We have very good evidence that mortality and complications are significantly less in individuals with prior infection or vaccination.

Public health communication involves an open and honest acceptance of uncertainty and discussion of choices as evidence evolves. In this discussion Prof Hsu said severe illness and deaths will rise as measures ease, but aiming for no deaths means the constraints on society will be extremely high: "We haven't talked about what we might want to accept in terms of the cost of living with Covid-19."

The UK reviewed all deaths from Covid between January and July 2021. There were 51,281 deaths in the period studied. There were 640 deaths in fully vaccinated individuals meaning that 98.8% of the deaths from Covid in this period occurred in people who were not fully vaccinated.

Early in the pandemic a study of AstraZeneca showed a surprising result. Individuals given a lower dose of vaccine by mistake had a larger immune response. The UK subsequently made a public health decision to increase the time between the first and second doses in an attempt to give as many people as possible some immunity. We now have very good evidence that this was the correct decision. An important example of using evidence to guide public health decisions rather than making assumptions.