Vaccines and the cold chain: is it too hot ... or too cold?

Carriage of Haemophilus influenzae among children attending childcare centres in Kuala Lumpur, Malaysia in the post vaccination era: A cross-sectional study

BACKGROUND

Haemophilus influenzae (H. influenzae) is a human upper respiratory tract colonizer which causes wide range of disease especially in children<5 years old and in the elderly. Although worldwide incidence in industrialised countries where Hib vaccination is commonly used has dropped sharply since implementation of H. influenzae type b (Hib) vaccination, there is limited data on the disease burden caused by H. influenzae in Malaysia post vaccination era. A change in predominant serotype from type b to non-b serotypes of H. influenzae in invasive diseases was reported worldwide. We investigated the carriage of H. influenzae post vaccination era among 2-4 years old.

METHODOLOGY

Randomly, we collected 436 oropharyngeal swabs from healthy children aged 2-4 years in 30 registered childcare centres in Kuala Lumpur (August 2018-May 2019). Informed consent and written questionnaires were obtained from parents. H. influenzae was identified by standard microbiological methods. Univariable analysis was carried out to describe variables associated with colonization. All variables with p < 0.25 were included in multivariable logistic regression model. A p value < 0.05 was considered significant.

RESULTS

A higher carriage rate was noted among the unvaccinated children (4/28; 14.3%) compared to vaccinated children (16/326; 4.9%) but were not statistically significant. The serotypes were type a (9; 37.5%), type b (5; 20.8%), type c (3; 12.5%), type d (2; 8%), type e (1; 4.2%) and type f (4; 16.7%). Variables like age, basic sanitation, immunization status, body mass index were included in multivariable logistic regression test since p values in univariate analysis were<0.25. Planned sewage system was found to be significant (Adjusted OR, 0.06; 95% CI, 0.01-0.46; p = 0.006).

CONCLUSION

Fewer carriage rates were observed among children post Hib vaccination era. Hib carriage is still possible after vaccination. The presence non-b serotypes may imply emerging replacement serotypes.

Turning up the heat: Effect of new vaccine for children's (VFC) program recommendations for use of temperature monitors upon incorrect product storage adverse event reporting

BACKGROUND

The Centers for Disease Control and Prevention (CDC) coordinates the Vaccines For Children (VFC) program, which provides free vaccines to qualified children in the US. In 2009, the CDC issued Vaccine Storage Requirements, which were later replaced (2012) with an interim guidance and toolkit for vaccine storage and handling. The guidance called for use of Digital Data Loggers (DDL) to monitor vaccine storage temperatures. We describe a change in frequency of Incorrect Product Storage Reports (IPSRs) following issuance of the 2009 CDC guidance.

METHODS

Merck & Co., Inc., Kenilworth, NJ, USA, systematically evaluates vaccine safety concerns for all products. The safety database was queried (01-Jan-2004 through 31-December-2016) to identify all IPSRs associated with 10 vaccines. We compared IPSRs received prior to and following the 2009 CDC guidance, comparing reports received from the US with those received from international sources during the same period.

RESULTS

Following the release of the DDL guidance, a progressive increase in IPSRs was identified in the US (1 report received in 2004, 12,993 reports in 2016). In contrast, non-US IPSRs - have not had a similar increase: no reports received in 2004, 216 reports received in 2016. US reports of IPSRs 2004 through 2016 account for 96% of reports worldwide. There were no serious reports found in the database in conjunction with IPSRs, nor were there any additional safety findings in any of the reports with additional events reported.

CONCLUSION

VFC DDL guidance was followed by an increase in IPSRs. No similar trend was seen outside the US (where no broad change in DDL guidance occurred). Despite the increase in IPSRs, there have been few associated adverse events (AEs) reported; no new safety concerns were identified. These findings suggest that the increase in IPSRs was associated with the introduction of use of DDLs, and suggests the need for further impact assessment.

Tools and approaches to ensure quality of vaccines throughout the cold chain

The Expanded Program on Immunization was designed 40 years ago for two types of vaccines: those that are heat stable but freeze sensitive and those that are stable to freezing but heat labile. A cold chain was developed for transport and storage of such vaccines and established in all countries, despite limited access to resources and electricity in the poorest areas. However, cold chain problems occur in all countries. Recent changes to vaccines and vaccine handling include development and introduction of new vaccines with a wide range of characteristics, improvement of heat stability of several basic vaccines, observation of vaccine freezing as a real threat, development of regulatory pathways for both vaccine development and the supply chain, and emergence of new temperature monitoring devices that can pinpoint and avoid problems. With such tools, public health groups have now encouraged development of vaccines labeled for use in flexible cold chains and these tools should be considered for future systems.

Human prophylactic vaccine adjuvants and their determinant role in new vaccine formulations

Adjuvants have been considered for a long time to be an accessory and empirical component of vaccine formulations. However, accumulating evidence of their crucial role in initiating and directing the immune response has increased our awareness of the importance of adjuvant research in the past decade. Nevertheless, the importance of adjuvants still is not fully realized by many researchers working in the vaccine field, who are involved mostly in the search for better target antigens. The choice of a proper adjuvant can be determinant for obtaining the best results for a given vaccine candidate, but it is restricted due to intellectual property and know-how issues. Consequently, in most cases the selected adjuvant continues to be the aluminum salt, which has a record of safety, but predominantly constitutes a delivery system (DS). Ideally, new strategies should combine immune potentiators (IP) and DS by mixing both compounds or by obtaining structures that contain both IP and DS. In addition, the term immune polarizer has been introduced as an essential concept in the vaccine design strategies. Here, we review the theme, with emphasis on the discussion of the few licensed new adjuvants, the need for safe mucosal adjuvants and the adjuvant/immunopotentiating activity of conjugation. A summary of toxicology and regulatory issues will also be discussed, and the Finlay Adjuvant Platform is briefly summarized.

Structural damages in adsorbed vaccines affected by freezing

This study was planned to evaluate structural damages in adsorbed vaccines affected by freezing using scanning electron microscopy and X-ray analysis of the elements. Randomly selected 42 vials of eight different types of WHO pre-qualified adsorbed freeze-sensitive vaccines from 10 manufacturers were included in the study. Vaccines were kept at 5 °C. Selected numbers of vials from each type were then exposed to -25 °C for 24 h periods. All samples were evaluated for their structure using scanning electron microscopy, X-ray analysis of the elements and precipitation time. Scanning electron microscopy of vaccines affected by freezing showed either smooth or rough surfaced conglomerates associated with phosphate content of the precipitate. These vaccines precipitated 2-15 times faster compared to non-frozen samples. Non-frozen samples showed uniform flocculent structure either dense or dispersed. X-ray analysis of precipitates in frozen samples confirmed that the precipitate is mainly aluminium clutters. Scanning electron microscopy confirmed that the lattice structure of bonds between adsorbent and the antigen is broken and aluminium forms conglomerates that grow in size and weight. The precipitation time of vaccines affected by freezing is 4.5 times faster on average compared to non-frozen samples. These facts form the basis of the "shake test".

Validation of the shake test for detecting freeze damage to adsorbed vaccines

OBJECTIVE

To determine the validity of the shake test for detecting freeze damage in aluminium-based, adsorbed, freeze-sensitive vaccines.

METHODS

A double-blind crossover design was used to compare the performance of the shake test conducted by trained health-care workers (HCWs) with that of phase contrast microscopy as a "gold standard". A total of 475 vials of 8 different types of World Health Organization prequalified freeze-sensitive vaccines from 10 different manufacturers were used. Vaccines were kept at 5 degrees C. Selected numbers of vials from each type were then exposed to -25 degrees C and -2 degrees C for 24-hour periods.

FINDINGS

There was complete concordance between HCWs and phase-contrast microscopy in identifying freeze-damaged vials and non-frozen samples. Non-frozen samples showed a fine-grain structure under phase contrast microscopy, but freeze-damaged samples showed large conglomerates of massed precipitates with amorphous, crystalline, solid and needle-like structures. Particles in the non-frozen samples measured from 1 microm (vaccines against diphtheria-tetanus-pertussis; Haemophilus influenzae type b; hepatitis B; diphtheria-tetanus-pertussis-hepatitis B) to 20 microm (diphtheria and tetanus vaccines, alone or in combination). By contrast, aggregates in the freeze-damaged samples measured up to 700 microm (diphtheria-tetanus-pertussis) and 350 microm on average.

CONCLUSION

The shake test had 100% sensitivity, 100% specificity and 100% positive predictive value in this study, which confirms its validity for detecting freeze damage to aluminium-based freeze-sensitive vaccines.

Improving temperature monitoring in the vaccine cold chain at the periphery: an intervention study using a 30-day electronic refrigerator temperature logger (Fridge-tag)

This intervention study was conducted in Albania to establish the superiority of the Fridge-tag (30-day electronic refrigerator temperature logger) against thermometers. Intervention sites used Fridge-tag and a modified temperature control record sheet, while control sites continued with their routine operation with thermometers. All refrigerators in both groups were equipped with downloadable electronic data loggers to record temperatures for reference. Focus group sessions were conducted with involved staff to discuss temperature monitoring, Fridge-tag use and its user-friendliness. Significant discrepancies were observed between thermometer readings and the electronic data loggers in control sites, while all alarms from Fridge-tag were confirmed in the intervention group. Thermometers are not sufficient to monitor temperatures in refrigerators since they miss the great majority of low and high alarms. Fridge-tag has proven to be an effective tool in providing health workers with the information they need to take the necessary actions when there are refrigerator temperature variations.

[The vaccine cold chain in a Valencian health department (Spain)]

OBJECTIVE

To evaluate the cold chain in the vaccination points of a health department in the autonomous region of Valencia, including training of the staff responsible for the cold chain.

METHOD

We performed a crosssectional study to review all the vaccination points (n = 50, with 68 refrigerators) of a health department in the autonomous region of Valencia. A structured questionnaire was used to gather information on the characteristics of the vaccination center, the staff responsible for the cold chain, the infrastructure and control of the elements composing the cold chain, the procedures used in vaccine conservation and handling, and knowledge of the staff.

RESULTS

The response rate was 100%. Most of the refrigerators were domestic refrigerators without alarm systems to alert staff to technical failure or electrical cuts (76.7%), open door alarm (98.5%), external thermometer (92.6%), automatic defrosting facilities (76.5%), internal temperature sensors or connection to emergency circuits (85.3%). Temperatures were mostly in the correct range (83.9%) and the vaccines were correctly located (88.2%). At least one staff member was responsible for the vaccines in all centers. Food was found in 33.8% of the refrigerators, vaccines were conserved on the vaccination table on the day of vaccination in 32.4%, and the temperature chart was not recorded daily in 75%.

CONCLUSION

The appropriate temperature was maintained in five out of every six refrigerators. However, the vaccine infrastructure in primary care centers, as well as training of the staff responsible for the cold chain, should be improved.

New horizons in adjuvants for vaccine development

Over the last decade, there has been a flurry of research on adjuvants for vaccines, and several novel adjuvants are now in licensed products or in late stage clinical development. The success of adjuvants in enhancing the immune response to recombinant antigens has led many researchers to re-focus their vaccine development programs. Successful vaccine development requires knowing which adjuvants to use and knowing how to formulate adjuvants and antigens to achieve stable, safe and immunogenic vaccines. For the majority of vaccine researchers this information is not readily available, nor is access to well-characterized adjuvants. In this review, we outline the current state of adjuvant research and development and how formulation parameters can influence the effectiveness of adjuvants.

Mantenimiento de la cadena del frío para las vacunas: una revisión sistemática

OBJECTIVE

Systematic immunization programmes mostly depend on the correct maintenance and manipulation of the vaccines to be used, i.e. perfect maintenance of the cold chain. Therefore, we decided to carry out a systematic review of the literature on the cold chain and vaccines, to identify daily practices in vaccine sites.

METHODS

A literature search was performed in the main medical databases for documents published between 1990 and 2005, including those performed by means of a survey and/or inspection of vaccine sites that provided the following data: a designated health officer, availability of a thermometer with maximums and minimums, refrigerator temperature at the time of the visit, and temperature control and registration. For all the variables, the mean prevalence was calculated with a 95% confidence interval.

RESULTS

Three hundred seventy-seven articles were found; 31 were initially selected and 13 were finally included. In 72.21% of the vaccine points, there was an officer responsible for the vaccines, but only 61.43% knew the optimal temperature range. Fifty-five percent of these points had a thermometer with maximums and minimums and only 26.88% carried out temperature controls and registrations at least once per day.

CONCLUSION

Important shortfalls were detected in cold chain maintenance in all selected articles, jeopardizing the effectiveness and efficiency of immunization programs.

A vaccine cold chain freezing study in PNG highlights technology needs for hot climate countries

Fourteen data loggers were packed with vaccine vials at the national vaccine store, Port Moresby, Papua New Guinea (PNG), and sent to peripheral locations in the health system. The temperatures that the data loggers recorded during their passage along the cold chain indicated that heat damage was unlikely, but that all vials were exposed to freezing temperatures at some time. The commonest place where freezing conditions existed was during transport. The freezing conditions were likely induced by packing the vials too close to the ice packs that were themselves too cold, and with insufficient insulation between them. This situation was rectified and a repeat dispatch of data loggers demonstrated that the system had indeed been rectified. Avoiding freeze damage becomes even more important as the price of freeze-sensitive vaccines increases with the introduction of more multiple-antigen vaccines. This low-cost high-tech method of evaluating the cold chain function is highly recommended for developing and industrialized nations and should be used on a regular basis to check the integrity of the vaccine cold chain. The study highlights the need for technological solutions to avoid vaccine freezing, particularly in hot climate countries.

Cold chain monitoring of OPV at transit levels in India: correlation of VVM and potency status

We have conducted a study to analyze monitoring of the cold chain of 674 OPV field samples collected at four different levels of vaccine distribution viz., immunization clinics, district stores, hospitals and Primary Health Centers (PHC) from states of Uttar Pradesh, Madhya Pradesh, and Delhi. The study design included: collection and scoring of vaccine vial monitor (VVM) status of the samples and testing for total oral polio virus concentration (TOPV) by standard WHO protocol. Ten samples each were exposed to 25 degrees C and 37 degrees C, and 10 samples as controls were kept at -20 degrees C. VVM were scored daily till they attained grade 4 and each sample was subsequently subjected to potency testing for individual polio serotypes 1, 2 and 3, and TOPV. Of the 674 samples tested it was observed that: samples from immunization clinics and district stores had an acceptable VVM score of grade 1 and 2; however the probable risk that a sub potent vaccine could have been administered was 2.15%. In 2.5% samples received from district stores vaccine had a VVM score of grade 3 (i.e., discard point), although vaccine when tested was found to be potent (i.e., leading to the vaccine wastage). With exposure to higher temperatures, VVM changed score to grade 2 and 3 when the vaccine was kept at 25 degrees C/37 degrees C, and the titres of individual serotypes 1, 2 and 3 and TOPV were beyond the acceptable limits. Important observations at the different levels of vaccine distribution network and correlation of VVM and potency status of OPV are discussed in the paper which will be of help to the EPI program managers at different transit levels.

Exposure of hepatitis B vaccine to freezing temperatures during transport to rural health centers in Mongolia

BACKGROUND

A previous evaluation of the Mongolian hepatitis B virus (HBV) infant vaccination program showed that only 70% of rural subjects developed protective antibody levels compared to 94% of urban subjects. The difference is likely due to damaged vaccine being administered to rural infants. HBV vaccine is heat-stable, but freezing destroys immunogenicity. The current study was designed to ascertain if HBV is subject to freezing temperatures during transport to rural health centers.

METHODS

During several time periods from 2001 to 2003, HBV vaccine transported from the national vaccine store to provincial stores and from two provincial stores to rural health centers was monitored for freezing using 3M Freeze Watch indicators.

RESULTS

Of 181 provincial-to-rural transports, 19% (95% CI 13-25%) resulted in freezing. One of 59 or 1.6% (95% CI 0-5.6%) of national-to-provincial store transports indicated freezing. In the second half of each substudy, freezing events diminished. Duration of transport was associated with freezing.

CONCLUSION

Identification of freezing temperatures during provincial-to-rural vaccine transport provides evidence that HBV vaccine is being damaged. This is the likely cause of the poor vaccine response in the Mongolian countryside. The authors speculate that packing vaccines for transport with ice taken directly from storage deep freezes at -20 degrees C is the cause of the freezing.

Vaccine storage practices in primary care physician offices: assessment and intervention

PURPOSE

To assess the proportion of primary care physician (PCP) offices meeting vaccine storage guidelines, identify factors associated with low compliance, and evaluate whether a quality improvement (QI) activity improves compliance.

METHODS

We examined compliance with guidelines of 721 PCP offices contracted with a national managed care organization in four cities. A QI activity (educational materials, written feedback, and distribution of thermometers) was conducted at baseline and a follow-up assessment occurred within 3 months.

RESULTS

Baseline compliance was relatively high, with >80% adherence to most guidelines. For example, 89% of offices had a thermometer; and 83% of temperatures were appropriate. Most units did not have vaccines stored in the door or food/biological materials in the unit (80% and 96%, respectively). Almost all vaccines had not expired. Multivariate analysis indicated that practice location, type of physician, participation in vaccine programs, and using guidelines were associated with compliance. For most of the compliance measures, pediatric offices had the highest compliance. Adherence to guidelines improved after the QI activity; the net change between pre- and post-intervention ranged from +1% to +19%. Measurements most impacted included temperature log posted (19% improvement in refrigerator; 16% improvement in freezer) and no vaccine stored in refrigerator door (14% improvement).

CONCLUSIONS

Despite generally high compliance, there are some opportunities for improvement in how PCPs store vaccines. Incorporating an intervention program in existing practice activities can improve storage practices. Further research is needed to determine the possible benefits of targeting interventions to certain types of providers who may be less knowledgeable about recommended guidelines.