Blocklisting - Interim Review

    SCHEDULE 5                                   
                                                                               
                        BLOCKLISTING SIX MONTHLY RETURN                        



1. Name of company
Acambis plc

2. Name of scheme
Acambis 1995 Unapproved Share Option Scheme

3. Period of return: From 01 July 2003 to 31 December 2003

4. Number and class of shares(s)(amount of stock/debt security)not issued under
scheme at end of last period:
179,969

5. Number of shares issued/allotted under scheme during period:
174,969

6. Balance under scheme not yet issued/allotted at end of period:
5,000

7. Number and class of share(s)(amount of stock/debt securities)originally
listed and the date of admission:
33,916,280 ordinary shares of 10p each

Date of admission: 30 November 1995

Please confirm total number of shares in issue at the end of the period in
order for us to update our records:
105,637,848

1. Name of company
Acambis plc

2. Name of scheme
Acambis 1996 Approved Share Option Scheme

3. Period of return: From 01 July 2003 to 31 December 2003

4. Number and class of shares(s)amount of stock/debt security) not issued under
scheme at end of last period:
479,508

5. Number of shares issued/allotted under scheme during period:
17,808

6. Balance under scheme not yet issued/allotted at end of period:
461,700

7. Number and class of share(s)(amount of stock/debt securities) originally
listed and the date of admission:
33,916,280 ordinary shares of 10p each

Date of admission: 30 November 1995

Please confirm total number of shares in issue at the end of the period in
order for us to update our records:
105,637,848

1. Name of company
Acambis plc

2. Name of scheme
Acambis 1995 Savings-Related Share Option Scheme

3. Period of return: From 01 July 2003 to 31 December 2003

4. Number and class of shares(s)amount of stock/debt security) not issued under
scheme at end of last period:
44,571

5. Number of shares issued/allotted under scheme during period:
4,469

6. Balance under scheme not yet issued/allotted at end of period:
40,102

7. Number and class of share(s)amount of stock/debt securities) originally
listed and the date of admission:
33,916,280 ordinary shares of 10p each

Date of admission: 30 November 1995

Please confirm total number of shares in issue at the end of the period in
order for us to update our records:
105,637,848

1. Name of company
Acambis plc

2. Name of scheme
Acambis 1999 Share Option Plan

3. Period of return: From 01 July 2003 to 31 December 2003

4. Number and class of shares(s) (amount of stock/debt security) not issued
under scheme at end of last period:
1,534,345

5. Number of shares issued/allotted under scheme during period:
610,619

6. Balance under scheme not yet issued/allotted at end of period:
923,726

7. Number and class of share(s)amount of stock/debt securities) originally
listed and the date of admission:
33,916,280 ordinary shares of 10p each

Date of admission: 30 November 1995

Please confirm total number of shares in issue at the end of the period in
order for us to update our records:
105,637,848

1. Name of company
Acambis plc

2. Name of scheme
OraVax 1990 Stock Incentive Plan

3. Period of return: From 01 July 2003 to 31 December 2003

4. Number and class of shares(s)amount of stock/debt security) not issued under
scheme at end of last period:
143,706

5. Number of shares issued/allotted under scheme during period:
Nil

6. Balance under scheme not yet issued/allotted at end of period:
143,706

7. Number and class of share(s) (amount of stock/debt securities) originally
listed and the date of admission:
33,916,280 ordinary shares of 10p each

Date of admission: 30 November 1995

Please confirm total number of shares in issue at the end of the period in
order for us to update our records:
105,637,848

1. Name of company
Acambis plc

2. Name of scheme
OraVax 1995 Stock Incentive Plan

3. Period of return: From 01 July 2003 to 31 December 2003

4. Number and class of shares(s)amount of stock/debt security) not issued under
scheme at end of last period:
150,000

5. Number of shares issued/allotted under scheme during period:
Nil

6. Balance under scheme not yet issued/allotted at end of period:
150,000

7. Number and class of share(s)amount of stock/debt securities) originally
listed and the date of admission:
33,916,280 ordinary shares of 10p each

Date of admission: 30 November 1995

Please confirm total number of shares in issue at the end of the period in
order for us to update our records:
105,637,848


Contact for queries: Elizabeth Brown
Address: Acambis plc, Peterhouse Technology Park, 100 Fulbourn Road, Cambridge
CB1 9PT
Name of person making return: Elizabeth Brown
Telephone: [phone]
Position of person making return: Company Secretary



END