Cold storage may be a challenge as some vaccines need to be stored at -80°C
Furthermore, there are some concerns that, depending on the Covid-19 vaccines that make it through to approval, there may be challenges associated with shipping and storage of the vaccine. RNA vaccines will need to be shipped on dry ice and stored in ultra-cold freezers. For example, mRNA is naturally unstable and needs to be stored frozen at below -20°C, and in some cases as cold as -80°C. This will complicate the global shipping and clinical use of RNA vaccines. Imperial College London, which is developing an RNA vaccine, has said that although, initially, its vaccine will be a frozen product, it will look to rapidly transition to a 2–8°C presentation, with a freeze-dried product as a longer-term option. Some vaccines, including the adenoviral vector vaccines, adjuvanted protein vaccines and inactivated whole virus vaccines, are expected to be stable at 2–8°C, so storage for those will be the same as for influenza vaccines.
Many countries are taking steps to help bolster vaccine manufacturing capacity. In the UK, in May 2020, the Government announced that it was investing up to £93m to open the UK’s first dedicated Vaccine Manufacturing and Innovation Centre (VMIC), 12 months early, in summer 2021. While the VMIC is being built, a rapid deployment facility has been established with a further investment of £38m, to begin manufacturing in 2020. Also the UK has made several other deals, including one with the Indian pharmaceutical company Wockhardt, in which the company has agreed to carry out the “fill and finish” stage of the manufacturing process, whereby the vaccine is dispensed into vials ready for distribution. Wockhardt has a manufacturing capacity of 400 million doses.
In addition, several of the main vaccine developers have made deals with manufacturers in different countries to secure sufficient capacity. For example, AstraZeneca, which has partnered with Oxford University on its vaccine, has reportedly made deals with more than 20 contract manufacturing organisations to hit its goal of delivering 2 billion doses by the end of 2021.
At least 60% of the population would have to be immune to achieve herd immunity, which could take years. Herd immunity describes the process by which at-risk individuals are protected from infection because they are surrounded by immune individuals, therefore minimising spread of the virus. Public health strategies to control Covid-19 generally fall into two categories: ‘mitigation’, which aims to achieve herd immunity by allowing the virus to spread through the population while mitigating disease burden so as not to overwhelm the health service, and ‘suppression’, which aims to drastically reduce SARS-CoV-2 transmission rates and halt endogenous transmission in the target population. Herd immunity becomes harder to achieve when vaccine-induced or natural immunity is partial or only for a limited period, or when logistical or other constraints limit roll-out or uptake of a vaccine.
However, once we have a mass vaccination program of the population, we should get back to normal, and we can look forward with great hope for 2021. In the meantime minimising the spread of Covid-19 by practising hand hygiene, social distancing and wearing face masks is the only way we have to reduce the number of people dying of the infection.
Adapted and updated from an article in the Pharmaceutical Journal 8 October 2020