Research Projects




Vaccination and effect on transmission ​

We determined the effectiveness of the AstraZeneca and Pfizer vaccines against the Delta variant of COVID-19. The CIPHA data allowed us to construct a time series of infected individuals stratified by vaccine-type and number of doses received. To this data we fitted a suitably stratified SIR model. We assumed that susceptible individuals who received a vaccine dose are protected against infection to some extent (the effectiveness). By fitting the model to the data we found that the effectiveness of the AstraZeneca vaccine is 38.13% and 63.72% for one and two doses respectively. The effectiveness of the Pfizer vaccine is 38.75% and 84.66% for one and two doses respectively.

Additionally, by comparing the Delta variant with the Alpha variant which was in circulation prior to Christmas, we determined that the Delta variant is 2.08 times more transmissible than the Alpha variant.

Future work will look at determining vaccine effectiveness across different age groups by employing a more direct calculation of the impact on the probability of infection of the different vaccines.

New Variant Evaluation ​

To determine the prevalance and descriptive features of positive COVID cases with new variants (particularly the Kent variant and possibly others as more data becomes available).​

Lateral Flow ​

Generalised linear mixed models using linked testing, and test and trace data to assess:

1. Is there any evidence that people with a lateral flow positive infect fewer people than those detected by PCR only (because they were asymptomatic and so transmission chains were broken)

2. Is there any evidence that people with negative LFT’s in the days before a positive PCR infect more people than those without a negative LFT? (I.e., is there any harm to a negative LFT in terms of what might appear to be less strict adherence to the distancing rules)​

3. Is there any evidence that people with a series of LFT tests before a positive PCR infect fewer people (since they are caught earlier, and so transmission chains broken)

4. Is there evidence that vaccinated individuals are less likely to transmit COVID-19, or to catch if from infected contacts.

Events Programme​

Evaluation of the National Opening up of events programme looking at the process as well as exploring attitudes towards social distancing and events.


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