Although the government's decision to lift all lockdown measures in England was widely anticipated to cause a major outbreak of disease and infection, the number of cases of Covid-19 has been declining over the past five days. Many believe this means that we are no longer at the peak. But the truth is more complex. It is the first epidemic to occur in highly vaccinated populations without any control measures. We are therefore in unfamiliar territory. It is unclear what the next two weeks will bring.It is not clear how large and long-lasting the current wave will be. Infections directly correlate with the number of people hospitalized and dying from Covid-19. It is impossible to predict when we will reach the peak infection rate or how long it will take for this to decrease. (If I had a pound to spend on every question, would I be able give away a lot?).We won't be able to tell if we are at the peak until we have passed it. This could take a few weeks. This is due to several factors. Although a peak can be measured in terms of the number infections, it is not something we see immediately. We can only see the results of infections. It takes at most a week to establish a pattern.A change in one stream of data might not reflect in another. The first data to be collected during a pandemic is the reported, diagnosed cases. However, these are often a week behind infections. While a drop in cases could indicate an increase in infections, it may also mean that there are issues with testing. If infection rates continue to rise, it is possible that there will be problems with people not getting tested and therefore, may have a decrease in positive cases. Even if tests are available, some people may not use them as often or in the same manner in the future.Hospital admissions provide more reliable data. These are usually a week behind cases. Even so, hospital admissions can fluctuate based on who has been infected. For example, younger people are less likely to be admitted to hospital. It takes several weeks for data from the Office for National Statistics (ONS), and Real-time Assessment of Community Transmissions (React), to be processed and published. These data will confirm that the prevalence of infection is decreasing once they are published.When we have a day with lower numbers of cases, people will ask if we are there yet. I will answer, "Yes, but wait a week." If the number of cases has fallen over the past week, I will point out rising hospital admissions. If they do fall and ONS or React data show that prevalence has fallen the week after peak, we can say that day with lower incidences was right after peak. However, peak in infections occurred a week earlier.Even more challenging is the fact that infection rates (the R number), are determined by contact rates and immunity. R = 1 at the peak of any wave. R drops as immunity to infection and vaccination increases. R rises when we make more contacts and change our behavior. It's a balance. It is possible to maintain R below 1, if we meet three people each day. But, it's not possible to do so if we meet five people each day.If everyone had Covid-19 immunity and everyone was still living at pre-pandemic levels of socialization, then the R number for the Delta version would be 6. It is currently 1.4. Recent surveys have shown that there is about half as much social contact as we had before the pandemic.It is quite possible that we will reach a peak. As our behaviours change, and our social contact increases, it will be possible to reach another peak. The delays will be important because we won't see immediate results from increased socialising on case number. We won't see the effects of the English restrictions on transmission until the week starting 2 August, if they have any. In the next few months, it is unlikely that there will be an increase to one peak and then a decrease in number. It will feel more like climbing a mountain than going over several hills.In the next few weeks, the epidemic will continue to rise and fall. There will be a significant increase in cases. Only by looking backwards can we see clearly where our journey has taken us. We will never know if we are there yet. Only we will be able say when we were there. That might not have been permanent.All this means that we are at greater risk of getting infected than ever before during the pandemic. The reason is because the incidence of infections is likely to increase. Vaccinations can prevent many deaths and keep people out of the hospital. However, there are still risks for individuals. It is important to get vaccinated.
