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Latex in pandemic vaccine syringes: TGA laboratory investigation
In October 2009 an anaphylactic reaction to the Panvax H1N1 pandemic influenza vaccine was reported in Western Australia in a person known to have a pre-existing latex allergy.
As the vaccine vials and the vaccine itself are latex free, the cause of the reaction was initially thought to be due to the presence of latex in the syringes used to deliver the vaccine, which have rubber-tipped plungers. The TGA undertook a series of laboratory investigations to ascertain if latex allergens could leach into the vaccine.
An advanced spectroscopy method was used to confirm that the plunger tip was indeed latex and also that it was coated with a silicone oil lubricant. This lubricant essentially acts as a barrier between the latex and solutions in the syringe.
No latex-containing proteins could be detected using high-performance liquid chromatography (HPLC). However since this method was considered not to be sufficiently sensitive for the detection of latex-containing proteins, syringe samples were sent to a laboratory in Estonia with particular expertise in latex allergen testing.
The results of testing conducted in this laboratory using an immunoassay kit detection method confirmed that latex was not leaching out of the plunger tips into solution, under a range of normal and exceptional conditions. The simulated test challenge conditions extended beyond the range of storage temperatures and hold times recommended in the ATAGI vaccination protocol for the H1N1 vaccine. No latex allergens were detected by the immunoassay kit in solution even after the latex tips had been cut into fine pieces.
The TGA therefore concluded that the reported adverse reaction was not the result of contact with latex allergens in the syringes provided in the influenza vaccination kits.
Detailed results of the testing may be viewed below.
Laboratory report: Investigation of Pandemic Vaccine Kit Syringes in relation to a suspected adverse reaction to latex following vaccination
12 October 2009
In October 2009 the TGA undertook testing of 1mL syringes supplied with Pandemic vaccine kits, following a report of a possible anaphylactic reaction to latex after vaccination with the Panvax vaccine in Western Australia.
The manufacturer of the syringes (Steeldrill) has confirmed that the plunger tip is made of natural latex rubber, with a silicone oil coating.
One box of 1 mL plastic syringes, each contained in a separate sealed labelled plastic bag. No sponsor or manufacturer details were declared on the labelling other than a trademark logo and the statement: Made in China. The following information was provided on the plastic bags:
- 1mL Sterile/EO Luerslip
- Code No. 930100 CE 0123
- Mfd Date: 20090315 Expiry Date: 20120315 Lot: 20090315
Initial testing of the syringes focussed on a comparison by HPLC1 of the syringes against non-latex containing syringes (Terumo 1mL Tuberculin syringes) when extracted with water or the Pandemic vaccine solution. A latex glove was also extracted with water to act as a control to determine whether peaks unique to the PVK syringe extracts were originating from the latex plunger tip or from other components in the syringes.
1 High Performance Liquid Chromatography with Photo Diode Array detection
The aim of this testing was to determine, firstly, whether there were any gross differences between the syringes and, secondly, whether any visible peaks could be identified as deriving from the latex plunger tip, in particular. This analysis was not expected to provide specific information about the presence of latex protein allergens in the extracts since no reference standards are available in the OLSS laboratories for identification purposes and any such protein would only be expected in nanogram amounts, which is well below the sensitivity of this technique. The following samples were prepared for HPLC analysis:
Sample 1 (+) Latex with vaccine
To each of 10 Pandemic Vaccine Kit (PVK) syringes, 0.1 mL of vaccine was drawn up using a hypodermic needle. The syringes were then inverted to ensure contact between the syringe plunger and vaccine and left for approximately 16 hours. After this time, the vaccine was removed from each of the 10 syringes and combined into a single sample solution of approximately 1 mL.
Sample 2 (-) Latex with vaccine
To each of 10 Terumo Latex Free syringes, 0.1 mL of vaccine was drawn up using a hypodermic needle. The syringes were treated as for sample 1 and the contents then combined into a single sample solution of approximately 1 mL.
Sample 3 (+) Latex with water
To each of 10 PVK syringes, 0.1 mL of water was drawn up using a hypodermic needle. The syringes were then inverted to ensure contact between the syringe plunger and water and left for approximately 16 hours. After this time, the water was removed from each of the 10 syringes and combined into a single sample solution of approximately 1 mL.
Sample 4 (-) Latex with water
To each of 10 Terumo Latex Free syringes, 0.1 mL of water was drawn up using a hypodermic needle. The syringes were treated as for sample 3 and the contents then combined into a single sample solution of approximately 1 mL.
Sample 5 (+) Latex plungers with vaccine
10 rubber plungers were removed from 10 PVK syringes and placed in a small flask. Approximately 1.5 mL of vaccine was added to the flask, which just covered the plungers. The plungers were left in contact with the vaccine for approximately 16 hours, after which time the vaccine was decanted from the flask and retained.
Sample 6 (+) Latex plungers with water
10 rubber plungers were removed from 10 PVK syringes and placed in a small flask. Approximately 1.5 mL of water was added to the flask, which just covered the plungers. The plungers were left in contact with the water for approximately 16 hours, after which time the water was decanted from the flask and retained.
Sample 7 Latex Control
A powder-free latex glove was chopped into pieces and extracted with water for 15 minutes after which time the water was decanted from the flask and retained.
HPLC profiles of the vaccine extracts (Samples 1 and 2) each showed the same 2 major peaks (see Figure 1 below). The earlier smaller peak has a similar UV profile to aspirin and is probably related to the thiomersal preservative although it does not appear to be thiomersal itself. It may be a hydrolysis product of thiomersal, e.g. thiosalicylate. The second, larger peak is presumed to be due to proteins, which would be consistent with its fairly non-specific UV profile. Both of these peaks originate from the vaccine, not from the syringe.
Figure 1: Vaccine extract of Panvax syringe
The water extracts (Sample 3 and 4) show a number of trace peaks as shown below in Figure 2. Note the very low absorption values on the y-axis. A number of the larger peaks are due to column bleed (see blank trace) and do not derive from the samples. The peaks unique to the Panvax syringe are indicated by arrows. The question of whether they are derived from the latex plunger or possibly other components of the syringe (e.g. plasticiser) is partly answered by a comparison against the latex (glove) control (Sample 7) as shown in Figure 3.
Figure 2: Water Extracts (Panvax syringe vs Terumo syringe comparator)
Figure 3: Water Extracts - Panvax syringe vs Latex comparator (glove)
Of the 7 trace peaks originating from the Panvax syringe potentially only one (see arrow) is common to the latex control based on retention time and UV spectra however the latter is not sufficiently complex to make this an unequivocal match.
Comparison of the water extracts of the Panvax syringes (Sample 3) vs the plunger tips (Sample 6) shows only one peak that is significantly increased in intensity, at a retention time of approximately 45 minutes, as shown below in Figure 4.
Figure 4: Water Extracts - Panvax syringe vs Panvax plunger tips
The HPLC analysis of water and vaccine extracts of the Panvax syringes shows that only a few trace organic compounds are extracted from the syringes. Of these peaks, only one minor peak is potentially derived from the latex in the plunger. The main conclusion that can be drawn from this HPLC study is that there are no significant organic contaminants being leached from the latex plunger of the syringe, however given that allergenic proteins would only need to be present in extremely small amounts to elicit an allergic reaction then this testing is not sufficiently sensitive conclusively exclude their presence. Further testing utilising more sensitive methods is recommended.
Report of further laboratory investigations of latex in Pandemic Vaccine Syringes undertaken by Icosagen Laboratories
19 October 2009
Natural rubber latex (NRL), which is derived from the rubber tree Hevea brasiliensis, contains particular proteins called allergens that can cause allergies in some people. Four NRL allergens have been identified as being clinically relevant to NRL allergy. These allergens are termed Hev b1, Hev b3, Hev b 5 and Hev b 6.02.
Icosagen's FITkit® test is based on a capture enzyme immunoassay method which is validated for extraction of the four latex allergens in phosphate buffered saline (PBS). The test uses highly purified and characterized allergens, and specific monoclonal antibodies, to quantify the four latex allergens in various products.
Icosagen tested 1mL syringes to determine whether latex leached out of the plunger tips of the syringes into PBS solution under a range of normal and 'worst case' contact conditions and extended holding times.
Test 1 - Certificate No QA090128
PBS was withdrawn into 3 syringes and extracted immediately. The extracted solutions were combined (sample 1) for testing by the FITkit®assay.
Test 2 - Certificate No QA090129
PBS was withdrawn into 3 syringes in each of 6 sample groups. Each sample group was incubated for either 2 hours (samples 2 and 3), 4 hours (samples 4 and 5) or 6 hours (samples 6 and 7). The extracted solutions from 3 syringes in each sample group were combined for testing by the FITkit®assay.
Test 3 - Certificate No QA090130
Pieces of the latex plunger from the syringes were cut up and exposed to PBS for either 2 hours (samples 8 and 9), 4 hours (samples 10 and 11) or 6 hours (samples 12 and 13) prior to testing the PBS extract by the FITkit®assay.
The four latex allergens (Hev b1, Hev b3, Hev b 5 and Hev b 6.02) were undetectable (UD) in the PBS extracts at the detection limits for each of the assays, as shown on the certificates of analysis for the three different test conditions:
- PBS withdrawn into syringes and immediately extracted. See test result shown on certificate No QA090128.
- PBS withdrawn into syringe and incubated for periods up to 6 hours prior to expulsion. See test result shown on certificate No QA090129.
- PBS incubated with cut-up pieces of the latex plunger for periods up to 6 hours. See test result shown on certificate No QA090130.
These results show that latex allergens could not be extracted from either the intact or disrupted latex plunger tips over a maximum contact period of 6 hours in phosphate buffered saline solutions at 4 degrees C. This demonstrates that there is an extremely low likelihood of latex allergens being present in the vaccine.
Certificates of analysis
- Certificate of analysis, No QA090128, Syringe (inner surface), Capture enzyme immunoassay method (pdf,326kb)
- Certificate of analysis, No QA090129, Syringes (inner surface), Capture enzyme immunoassay method (pdf,377kb)
- Certificate of analysis, No QA090130, Syringe plunger pistons, Capture enzyme immunoassay method (pdf,373kb)