Preserving the integrity of the cold chain

With annual COVID-19 booster jabs almost inevitable, GP surgeries are likely to play a key role in delivering the ongoing vaccination programme. The logistical challenges – including maintaining the cold chain – posed by this should not be underestimated

The success of the UK’s COVID vaccination programme is widely acknowledged, with more than 50 milllion doses already administered.

As people take their first steps back into high street shops, pubs and workplaces, hopes are understandably high that this latest lockdown will be the last. However, notes of caution are already being sounded. It is clear that future social freedoms are clearly predicated on how successfully we control the spread of the virus in the future.

In a recent BMJ interview, Anthony Harnden, a member of the Joint Committee on Vaccination and Immunisation, suggested additional boosters would be needed this year to guard against a new variant or as a precautionary measure to prevent a third wave of the outbreak. He added that, while difficult to predict the precise requirements, it was likely there would be a need for an annual booster ‘for a while’.¹

With the cost of COVID vaccine-related investment already estimated at almost £12 billion by the National Audit Office, it would be difficult to overstate the financial burden of a long-term mass vaccination programme, not to mention the scale of the logistical challenge it would present.

Any contribution to mitigating the pressures on already overstretched health and social care budgets is therefore to be welcomed – and avoiding the waste of these incredibly valuable new vaccines is one way in which general practice nurses can play their part.

Much has been written about the ‘last mile’ of the cold chain challenge, specifically in relation to the Pfizer vaccine, because of its low temperature requirements, but perhaps not enough consideration has been given to the challenge of keeping the vaccine cool at the point of administration.

So, why does this matter?

THE IMPACT OF BADLY STORED VACCINES

Figures for 2018 show that vaccine wastage had a list price value of around £6.3 million. In terms of doses, about half of the reported incidents were avoidable, with many relating to incorrect storage.² This is before COVID-19 vaccines are taken into account.

The active chemicals in all vaccines and other medication can change in molecular form when exposed to different temperatures, and the current COVID vaccines from Pfizer, Moderna and Oxford/AstraZeneca are no different. For example, measles and the combined MMR vaccines could have their potency reduced by higher temperatures, while the Hepatitis B and HPV vaccines are sensitive to temperatures which are too cold.

Vaccines naturally biodegrade over time and being stored outside their recommended temperature range may speed up this loss of potency. This impact cannot be reversed, and a vaccine may then fail to provoke the desired immune response and give protection.

AVOID WASTE AND PROTECT THE PUBLIC

The ‘cold chain’ is designed to protect vaccines and other biologics from point of manufacture, through their transportation to pharmacy wholesalers or distribution centres, where they must be safely stored before being distributed to clinical locations such as GP surgeries. During this process Pfizer’s vaccine must be kept at –70°C, while Moderna has said that its vaccine needs to be kept frozen too, at –20° C. However, all of this is pointless if things go wrong in the final link of the chain – GP surgeries, pharmacies and hospitals. Once delivered, all of the currently available vaccines can be stored for up to five days within strict 2 to 8°C parameters.

Failure to store vaccines according to manufacturers’ strict temperature requirements can invalidate the expiry date and cause manufacturers to disclaim responsibility for any apparent failure of the vaccine, as the safety and effectiveness of such medicines can be significantly compromised or unknown.

To minimise this risk, GP practices should have named individuals responsible and accountable for the receipt and storage of vaccines and other heat sensitive medicines, and the monitoring and recording of fridge and ambient room temperatures.

Crucially, refrigerators used for the storage of medicines must be designed specifically for that purpose. Standard domestic refrigerators cannot be used for storing cold chain products for several reasons, including an uneven temperature distribution (as a result of minimal air circulation) and a normal operating range of between 0°C and 10°C. The refrigerator used must also be of an appropriate size for the quantity of stock to be stored i.e. filled to no more than 75% capacity to allow adequate air circulation. It must also be reserved exclusively for the storage of vaccines and other pharmaceutical products and not used to store food, blood, milk, drink, or anything else representing a contamination risk.

Care must also be taken to ensure the refrigeration unit is sited in a well-ventilated room maintained between 10°C and 25°C, away from external windows and all heat sources e.g. radiators or direct sunlight, and at least 5-10 cm from walls and other units. To ensure its ongoing effectiveness, any vaccine refrigeration unit must be serviced according to manufacturer’s instructions and have its integral thermometer independently calibrated to ensure readings are true. Finally, the medical refrigerator must be cleaned regularly, and the internal stock should be stored according to first expiry.

MAINTAINING PUBLIC TRUST

Despite the positivity surrounding the new COVID-19 vaccines, research by the journal Nature revealed that unfounded anti-vaccine messages on social media were more effective at swaying undecided groups than proven scientific research.³

The World Health Organization (WHO) has also sounded a note of caution, listing what it calls ‘vaccine hesitancy’ as one of the top ten threats to global health.⁴

Practice nurses can play a small but significant part in maintaining the fragile public trust in vaccines by strictly following guidelines for the storage of vaccines to avoid waste and ensure their efficacy when administered to adults and children.

The global pandemic has shone fresh light on the vital role that vaccines play in maintaining healthy communities, taking pressure off overburdened health services, and keeping economies afloat.

The scale of the COVID-19 vaccination programme is unprecedented and the pressure on health locations to support it is unlikely to abate any time soon. In light of this, it has arguably never been more important for to embed good practice in daily routines and procedures to ensure not one batch of vaccines is wasted.

REFERENCES

1. Mahase E. Covid-19: Booster dose will be needed in autumn to avoid winter surge, says government adviser. BMJ 2021;372:n664 https://www.bmj.com/content/372/bmj.n664

2. Public Health England. Vaccine update 2019;297: 8 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/820795/PHE_vaccine_update_297_July_2019.pdf

3. Borden Y. Public trust in vaccines. Nature Milestones: Vaccines. 2020;S23 https://www.nature.

com/articles/d42859-020-00024-5

4. WHO. Ten threats to global health in 2019. https://www.who.int/news-room/spotlight/ten-threats-to-global-health-in-2019